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<li class="navelem"><a class="el" href="dir_58e412aa7ace8e71fc01678dc8765e7c.html">transport</a></li><li class="navelem"><a class="el" href="dir_a98fddea045b8b2df4350ebb1d483bf8.html">struc</a></li>  </ul>
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<a href="ipc__transport__structured_2src_2ipc_2transport_2struc_2serializer_8hpp.html">Go to the documentation of this file.</a><div class="fragment"><div class="line"><a id="l00001" name="l00001"></a><span class="lineno">    1</span><span class="comment">/* Flow-IPC: Structured Transport</span></div>
<div class="line"><a id="l00002" name="l00002"></a><span class="lineno">    2</span><span class="comment"> * Copyright (c) 2023 Akamai Technologies, Inc.; and other contributors.</span></div>
<div class="line"><a id="l00003" name="l00003"></a><span class="lineno">    3</span><span class="comment"> * Each commit is copyright by its respective author or author&#39;s employer.</span></div>
<div class="line"><a id="l00004" name="l00004"></a><span class="lineno">    4</span><span class="comment"> *</span></div>
<div class="line"><a id="l00005" name="l00005"></a><span class="lineno">    5</span><span class="comment"> * Licensed under the MIT License:</span></div>
<div class="line"><a id="l00006" name="l00006"></a><span class="lineno">    6</span><span class="comment"> *</span></div>
<div class="line"><a id="l00007" name="l00007"></a><span class="lineno">    7</span><span class="comment"> * Permission is hereby granted, free of charge, to any person obtaining a copy</span></div>
<div class="line"><a id="l00008" name="l00008"></a><span class="lineno">    8</span><span class="comment"> * of this software and associated documentation files (the &quot;Software&quot;), to deal</span></div>
<div class="line"><a id="l00009" name="l00009"></a><span class="lineno">    9</span><span class="comment"> * in the Software without restriction, including without limitation the rights</span></div>
<div class="line"><a id="l00010" name="l00010"></a><span class="lineno">   10</span><span class="comment"> * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell</span></div>
<div class="line"><a id="l00011" name="l00011"></a><span class="lineno">   11</span><span class="comment"> * copies of the Software, and to permit persons to whom the Software is</span></div>
<div class="line"><a id="l00012" name="l00012"></a><span class="lineno">   12</span><span class="comment"> * furnished to do so, subject to the following conditions:</span></div>
<div class="line"><a id="l00013" name="l00013"></a><span class="lineno">   13</span><span class="comment"> *</span></div>
<div class="line"><a id="l00014" name="l00014"></a><span class="lineno">   14</span><span class="comment"> * The above copyright notice and this permission notice shall be included in</span></div>
<div class="line"><a id="l00015" name="l00015"></a><span class="lineno">   15</span><span class="comment"> * all copies or substantial portions of the Software.</span></div>
<div class="line"><a id="l00016" name="l00016"></a><span class="lineno">   16</span><span class="comment"> *</span></div>
<div class="line"><a id="l00017" name="l00017"></a><span class="lineno">   17</span><span class="comment"> * THE SOFTWARE IS PROVIDED &quot;AS IS&quot;, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR</span></div>
<div class="line"><a id="l00018" name="l00018"></a><span class="lineno">   18</span><span class="comment"> * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,</span></div>
<div class="line"><a id="l00019" name="l00019"></a><span class="lineno">   19</span><span class="comment"> * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE</span></div>
<div class="line"><a id="l00020" name="l00020"></a><span class="lineno">   20</span><span class="comment"> * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER</span></div>
<div class="line"><a id="l00021" name="l00021"></a><span class="lineno">   21</span><span class="comment"> * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,</span></div>
<div class="line"><a id="l00022" name="l00022"></a><span class="lineno">   22</span><span class="comment"> * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN</span></div>
<div class="line"><a id="l00023" name="l00023"></a><span class="lineno">   23</span><span class="comment"> * THE SOFTWARE. */</span></div>
<div class="line"><a id="l00024" name="l00024"></a><span class="lineno">   24</span><span class="comment"></span> </div>
<div class="line"><a id="l00025" name="l00025"></a><span class="lineno">   25</span><span class="comment">/// @file</span></div>
<div class="line"><a id="l00026" name="l00026"></a><span class="lineno">   26</span><span class="comment"></span> </div>
<div class="line"><a id="l00027" name="l00027"></a><span class="lineno">   27</span><span class="comment">// Not compiled: for documentation only.  Contains concept docs as of this writing.</span></div>
<div class="line"><a id="l00028" name="l00028"></a><span class="lineno">   28</span><span class="preprocessor">#ifndef IPC_DOXYGEN_ONLY</span></div>
<div class="line"><a id="l00029" name="l00029"></a><span class="lineno">   29</span><span class="keyword">static_assert</span>(<span class="keyword">false</span>, <span class="stringliteral">&quot;As of this writing this is a documentation-only \&quot;header\&quot; &quot;</span></div>
<div class="line"><a id="l00030" name="l00030"></a><span class="lineno">   30</span>                       <span class="stringliteral">&quot;(the \&quot;source\&quot; is for humans and Doxygen only).&quot;</span>);</div>
<div class="line"><a id="l00031" name="l00031"></a><span class="lineno">   31</span><span class="preprocessor">#else </span><span class="comment">// ifdef IPC_DOXYGEN_ONLY</span></div>
<div class="line"><a id="l00032" name="l00032"></a><span class="lineno">   32</span> </div>
<div class="line"><a id="l00033" name="l00033"></a><span class="lineno">   33</span><span class="keyword">namespace </span><a class="code hl_namespace" href="namespaceipc_1_1transport_1_1struc.html">ipc::transport::struc</a></div>
<div class="line"><a id="l00034" name="l00034"></a><span class="lineno">   34</span>{</div>
<div class="line"><a id="l00035" name="l00035"></a><span class="lineno">   35</span> </div>
<div class="line"><a id="l00036" name="l00036"></a><span class="lineno">   36</span><span class="comment">// Types.</span></div>
<div class="line"><a id="l00037" name="l00037"></a><span class="lineno">   37</span><span class="comment"></span> </div>
<div class="line"><a id="l00038" name="l00038"></a><span class="lineno">   38</span><span class="comment">/**</span></div>
<div class="line"><a id="l00039" name="l00039"></a><span class="lineno">   39</span><span class="comment"> * A documentation-only *concept* defining the behavior of an object capable of zero-copy-serializing,</span></div>
<div class="line"><a id="l00040" name="l00040"></a><span class="lineno">   40</span><span class="comment"> * similar to `capnp::MessageBuilder` but geared to transmission over pipe-like IPC transports.</span></div>
<div class="line"><a id="l00041" name="l00041"></a><span class="lineno">   41</span><span class="comment"> * At its simplest it is conceptually identical to `MessageBuilder` but, crucially, also allows for the (optional)</span></div>
<div class="line"><a id="l00042" name="l00042"></a><span class="lineno">   42</span><span class="comment"> * 2-tier architecture wherein only a small handle is transmitted over an IPC pipe, while the user-controlled</span></div>
<div class="line"><a id="l00043" name="l00043"></a><span class="lineno">   43</span><span class="comment"> * tree is stored in a single central location (most likely in shared memory) and is itself never copied.</span></div>
<div class="line"><a id="l00044" name="l00044"></a><span class="lineno">   44</span><span class="comment"> * The following discussion assumes sophisticated familiarity with capnp (Cap&#39;n Proto).</span></div>
<div class="line"><a id="l00045" name="l00045"></a><span class="lineno">   45</span><span class="comment"> *</span></div>
<div class="line"><a id="l00046" name="l00046"></a><span class="lineno">   46</span><span class="comment"> * @see Struct_reader, the counterpart concept.</span></div>
<div class="line"><a id="l00047" name="l00047"></a><span class="lineno">   47</span><span class="comment"> *</span></div>
<div class="line"><a id="l00048" name="l00048"></a><span class="lineno">   48</span><span class="comment"> * The above description may sound quite a lot like the capnp-supplied `virtual` interface,</span></div>
<div class="line"><a id="l00049" name="l00049"></a><span class="lineno">   49</span><span class="comment"> * `capnp::MessageBuilder`.  And some of this concept&#39;s most prominent impls have conceptual counterparts</span></div>
<div class="line"><a id="l00050" name="l00050"></a><span class="lineno">   50</span><span class="comment"> * in the implementing classes of `MessageBuilder`; for example Heap_fixed_builder</span></div>
<div class="line"><a id="l00051" name="l00051"></a><span class="lineno">   51</span><span class="comment"> * evokes `capnp::MallocMessageBuilder` (and in fact internally uses a custom `MessageBuilder` quite</span></div>
<div class="line"><a id="l00052" name="l00052"></a><span class="lineno">   52</span><span class="comment"> * similar to `MallocMessageBuilder`).</span></div>
<div class="line"><a id="l00053" name="l00053"></a><span class="lineno">   53</span><span class="comment"> *</span></div>
<div class="line"><a id="l00054" name="l00054"></a><span class="lineno">   54</span><span class="comment"> * Indeed, at its simplest, Struct_builder is conceptually similar to `capnp::MessageBuilder`:</span></div>
<div class="line"><a id="l00055" name="l00055"></a><span class="lineno">   55</span><span class="comment"> *   - It must store a concretely-typed `MessageBuilder` that the user would mutate via</span></div>
<div class="line"><a id="l00056" name="l00056"></a><span class="lineno">   56</span><span class="comment"> *     payload_msg_builder(), which returns a pointer to said `MessageBuilder`.  One would typically</span></div>
<div class="line"><a id="l00057" name="l00057"></a><span class="lineno">   57</span><span class="comment"> *     mutate it via `-&gt;initRoot&lt;SomeUserSchema&gt;()` and so on.</span></div>
<div class="line"><a id="l00058" name="l00058"></a><span class="lineno">   58</span><span class="comment"> *     Through this one can set the structured data within the data structure.</span></div>
<div class="line"><a id="l00059" name="l00059"></a><span class="lineno">   59</span><span class="comment"> *   - As one does so, the payload bits are set (by capnp-generated code) in zero-copy fashion inside 1+</span></div>
<div class="line"><a id="l00060" name="l00060"></a><span class="lineno">   60</span><span class="comment"> *     segments somewhere in RAM (or other vaddr-mapped storage), without any user intervention outside of the</span></div>
<div class="line"><a id="l00061" name="l00061"></a><span class="lineno">   61</span><span class="comment"> *     actual capnp mutator calls.</span></div>
<div class="line"><a id="l00062" name="l00062"></a><span class="lineno">   62</span><span class="comment"> *   - One can then obtain the resulting serialization -- consisting of 1+ segments in RAM.</span></div>
<div class="line"><a id="l00063" name="l00063"></a><span class="lineno">   63</span><span class="comment"> *     `MessageBuilder::getSegmentsForOutput()` is how it&#39;s done in `MessageBuilder`;</span></div>
<div class="line"><a id="l00064" name="l00064"></a><span class="lineno">   64</span><span class="comment"> *     while we have emit_serialization().</span></div>
<div class="line"><a id="l00065" name="l00065"></a><span class="lineno">   65</span><span class="comment"> *</span></div>
<div class="line"><a id="l00066" name="l00066"></a><span class="lineno">   66</span><span class="comment"> * Ultimately, in fact, any Struct_builder is always implemented internally as a wrapper around</span></div>
<div class="line"><a id="l00067" name="l00067"></a><span class="lineno">   67</span><span class="comment"> * one `MessageBuilder` or another (quite possibly a custom one also implemented by us).</span></div>
<div class="line"><a id="l00068" name="l00068"></a><span class="lineno">   68</span><span class="comment"> *</span></div>
<div class="line"><a id="l00069" name="l00069"></a><span class="lineno">   69</span><span class="comment"> * So why does Struct_builder exist, outside of cosmetic niceties?  Answer: It is designed around (the possiblity of)</span></div>
<div class="line"><a id="l00070" name="l00070"></a><span class="lineno">   70</span><span class="comment"> * two-tier serialization (discussed in &quot;Copying versus zero-copy&quot; below), namely for SHM-based IPC.</span></div>
<div class="line"><a id="l00071" name="l00071"></a><span class="lineno">   71</span><span class="comment"> * `MessageBuilder`, alone, does not supply the necessary facilities to make the SHM/two-tier use-case easy;</span></div>
<div class="line"><a id="l00072" name="l00072"></a><span class="lineno">   72</span><span class="comment"> * we do.  A good way of looking at it is: Struct_builder allows one to combine two `capnp::MessageBuilder`s,</span></div>
<div class="line"><a id="l00073" name="l00073"></a><span class="lineno">   73</span><span class="comment"> * using one for user-facing mutation pre-transmission-over-IPC; and the other `MessageBuilder` for the tiny</span></div>
<div class="line"><a id="l00074" name="l00074"></a><span class="lineno">   74</span><span class="comment"> * SHM-handle that&#39;s copied over at transmission-over-IPC time.  payload_msg_builder() provides access to the</span></div>
<div class="line"><a id="l00075" name="l00075"></a><span class="lineno">   75</span><span class="comment"> * user-mutating; emit_serialization() provides access to the IPC-transmissible bits.  When the serialization</span></div>
<div class="line"><a id="l00076" name="l00076"></a><span class="lineno">   76</span><span class="comment"> * strategy is 1-tier, Struct_builder is essentially isomorphic to `MessageBuilder`.  When it is 2-tier,</span></div>
<div class="line"><a id="l00077" name="l00077"></a><span class="lineno">   77</span><span class="comment"> * it adds significant conceptual value.</span></div>
<div class="line"><a id="l00078" name="l00078"></a><span class="lineno">   78</span><span class="comment"> *</span></div>
<div class="line"><a id="l00079" name="l00079"></a><span class="lineno">   79</span><span class="comment"> * In any case a Struct_builder formally works as follows.</span></div>
<div class="line"><a id="l00080" name="l00080"></a><span class="lineno">   80</span><span class="comment"> *   - Construct it via `Struct_builder(const Struct_builder::Config&amp;)` ctor form, where Struct_builder::Config</span></div>
<div class="line"><a id="l00081" name="l00081"></a><span class="lineno">   81</span><span class="comment"> *     is a small (cheaply-copyable) type storing a few knobs controlling Struct_builder behavior.</span></div>
<div class="line"><a id="l00082" name="l00082"></a><span class="lineno">   82</span><span class="comment"> *     (It exists to be able to easily store the same set of knob values to keep reusing it, as well to ease generic</span></div>
<div class="line"><a id="l00083" name="l00083"></a><span class="lineno">   83</span><span class="comment"> *     programming.  The knob set for one Struct_builder impl may hugely differ from another&#39;s.</span></div>
<div class="line"><a id="l00084" name="l00084"></a><span class="lineno">   84</span><span class="comment"> *     Informally, Config is likely to be an *aggregate* `struct` hence aggregate-initializable</span></div>
<div class="line"><a id="l00085" name="l00085"></a><span class="lineno">   85</span><span class="comment"> *     (e.g., `Config c{ knob1_val, knob2_val };`).</span></div>
<div class="line"><a id="l00086" name="l00086"></a><span class="lineno">   86</span><span class="comment"> *     - This implies that each Struct_builder impl shall feature this ctor form, such that it is possible/advised</span></div>
<div class="line"><a id="l00087" name="l00087"></a><span class="lineno">   87</span><span class="comment"> *       to pass the same (equal by value) Config as args each time with no ill effects within reason.</span></div>
<div class="line"><a id="l00088" name="l00088"></a><span class="lineno">   88</span><span class="comment"> *     - Struct_builder must also be efficiently move-constructible and move-assignable but not copyable.</span></div>
<div class="line"><a id="l00089" name="l00089"></a><span class="lineno">   89</span><span class="comment"> *   - Call payload_msg_builder() which returns a `MessageBuilder*`; mutate the pointee as usual</span></div>
<div class="line"><a id="l00090" name="l00090"></a><span class="lineno">   90</span><span class="comment"> *     (likely `initRoot&lt;SomeUserSchema&gt;()` and so on).</span></div>
<div class="line"><a id="l00091" name="l00091"></a><span class="lineno">   91</span><span class="comment"> *   - Call emit_serialization().  This emits a #Segment_ptrs container which is basically a</span></div>
<div class="line"><a id="l00092" name="l00092"></a><span class="lineno">   92</span><span class="comment"> *     list of *pointers* to `flow::util::Blob` (which is much like `vector&lt;uint8_t&gt;`), where each `Blob` therein</span></div>
<div class="line"><a id="l00093" name="l00093"></a><span class="lineno">   93</span><span class="comment"> *     is stored within `*this` until destruction.</span></div>
<div class="line"><a id="l00094" name="l00094"></a><span class="lineno">   94</span><span class="comment"> *   - Transmit each `Blob`, in order, by copying into a transport (e.g., by using a Blob_sender).</span></div>
<div class="line"><a id="l00095" name="l00095"></a><span class="lineno">   95</span><span class="comment"> *     Note that the transport must be capable of transmitting these blobs while maintaining ordering and</span></div>
<div class="line"><a id="l00096" name="l00096"></a><span class="lineno">   96</span><span class="comment"> *     boundaries and without barfing due to anything, including a single blob, being too large.</span></div>
<div class="line"><a id="l00097" name="l00097"></a><span class="lineno">   97</span><span class="comment"> *     (It is up to the Struct_builder impl to document any such limitations it might have.)</span></div>
<div class="line"><a id="l00098" name="l00098"></a><span class="lineno">   98</span><span class="comment"> *   - (`*this` can now be destroyed.)</span></div>
<div class="line"><a id="l00099" name="l00099"></a><span class="lineno">   99</span><span class="comment"> *   - Use the counterpart Struct_reader on the other side of this transport to obtain access</span></div>
<div class="line"><a id="l00100" name="l00100"></a><span class="lineno">  100</span><span class="comment"> *     to this serialization.  See Struct_reader doc header.</span></div>
<div class="line"><a id="l00101" name="l00101"></a><span class="lineno">  101</span><span class="comment"> *</span></div>
<div class="line"><a id="l00102" name="l00102"></a><span class="lineno">  102</span><span class="comment"> * The following is an optional continuation of the lifecycle of a Struct_builder.  There are two</span></div>
<div class="line"><a id="l00103" name="l00103"></a><span class="lineno">  103</span><span class="comment"> * varieties: read-only and read/write.  The read-only lifecycle continuation is as follows:</span></div>
<div class="line"><a id="l00104" name="l00104"></a><span class="lineno">  104</span><span class="comment"> *   - Call emit_serialization() again.</span></div>
<div class="line"><a id="l00105" name="l00105"></a><span class="lineno">  105</span><span class="comment"> *   - Transmit the emitted `Blob`s again into some transport again (the same one, a different one, whatever).</span></div>
<div class="line"><a id="l00106" name="l00106"></a><span class="lineno">  106</span><span class="comment"> *   - Again use the counterpart Struct_reader on the other side of this transport to obtain access</span></div>
<div class="line"><a id="l00107" name="l00107"></a><span class="lineno">  107</span><span class="comment"> *     to this serialization.</span></div>
<div class="line"><a id="l00108" name="l00108"></a><span class="lineno">  108</span><span class="comment"> *   - Repeat as many times as desired.</span></div>
<div class="line"><a id="l00109" name="l00109"></a><span class="lineno">  109</span><span class="comment"> *</span></div>
<div class="line"><a id="l00110" name="l00110"></a><span class="lineno">  110</span><span class="comment"> * I.e., a message -- once mutated and serialized/sent -- can be re-sent as many times as desired.</span></div>
<div class="line"><a id="l00111" name="l00111"></a><span class="lineno">  111</span><span class="comment"> * The concept implementer shall strive to make emit_serialization() be reasonably performant on the 2nd, 3rd, ...</span></div>
<div class="line"><a id="l00112" name="l00112"></a><span class="lineno">  112</span><span class="comment"> * call.  While all capnp serializations are zero-copy (before copying into transport), no particular care</span></div>
<div class="line"><a id="l00113" name="l00113"></a><span class="lineno">  113</span><span class="comment"> * should be required to accomplish this; at worst it&#39;s a matter of grabbing the segment pointers and emitting</span></div>
<div class="line"><a id="l00114" name="l00114"></a><span class="lineno">  114</span><span class="comment"> * them into a user-provided target container.  There typically will be only a few; with SHM-based builders</span></div>
<div class="line"><a id="l00115" name="l00115"></a><span class="lineno">  115</span><span class="comment"> * just one.</span></div>
<div class="line"><a id="l00116" name="l00116"></a><span class="lineno">  116</span><span class="comment"> *</span></div>
<div class="line"><a id="l00117" name="l00117"></a><span class="lineno">  117</span><span class="comment"> * Lastly, then, the read/write lifecycle continuation is as follows:</span></div>
<div class="line"><a id="l00118" name="l00118"></a><span class="lineno">  118</span><span class="comment"> *   - (Only if it is a SHM-based serialization) Receive some guarantee that the recipient is done reading</span></div>
<div class="line"><a id="l00119" name="l00119"></a><span class="lineno">  119</span><span class="comment"> *     the deserialization (e.g., an ack message).</span></div>
<div class="line"><a id="l00120" name="l00120"></a><span class="lineno">  120</span><span class="comment"> *     - If it is not SHM-based, then this is not necessary: The deserialization is fully a copy of `*this`</span></div>
<div class="line"><a id="l00121" name="l00121"></a><span class="lineno">  121</span><span class="comment"> *       serialization, so mutating the original has no effect on the recipient.</span></div>
<div class="line"><a id="l00122" name="l00122"></a><span class="lineno">  122</span><span class="comment"> *     - (Wait, what?  SHM-based?  Yes: See &quot;Copying versus zero-copy&quot; section below.)</span></div>
<div class="line"><a id="l00123" name="l00123"></a><span class="lineno">  123</span><span class="comment"> *   - Further mutate the payload `MessageBuilder` (as accessed via payload_msg_builder()).</span></div>
<div class="line"><a id="l00124" name="l00124"></a><span class="lineno">  124</span><span class="comment"> *   - Call emit_serialization() again.</span></div>
<div class="line"><a id="l00125" name="l00125"></a><span class="lineno">  125</span><span class="comment"> *   - Transmit the emitted `Blob`s into some transport (the same one, a different one, whatever) -- again.</span></div>
<div class="line"><a id="l00126" name="l00126"></a><span class="lineno">  126</span><span class="comment"> *   - Again use the counterpart Struct_reader on the other side of this transport to obtain access</span></div>
<div class="line"><a id="l00127" name="l00127"></a><span class="lineno">  127</span><span class="comment"> *     to this serialization.</span></div>
<div class="line"><a id="l00128" name="l00128"></a><span class="lineno">  128</span><span class="comment"> *   - Repeat as many times as desired.</span></div>
<div class="line"><a id="l00129" name="l00129"></a><span class="lineno">  129</span><span class="comment"> *</span></div>
<div class="line"><a id="l00130" name="l00130"></a><span class="lineno">  130</span><span class="comment"> * I.e., it is much like the read-only variant above, except in a SHM-based builder variety one must</span></div>
<div class="line"><a id="l00131" name="l00131"></a><span class="lineno">  131</span><span class="comment"> * take concurrent read/write access into consideration.</span></div>
<div class="line"><a id="l00132" name="l00132"></a><span class="lineno">  132</span><span class="comment"> *</span></div>
<div class="line"><a id="l00133" name="l00133"></a><span class="lineno">  133</span><span class="comment"> * ### Copying versus zero-copy ###</span></div>
<div class="line"><a id="l00134" name="l00134"></a><span class="lineno">  134</span><span class="comment"> * You may note that the above unapologetically declares that the serialization&#39;s blobs must be *copied* into</span></div>
<div class="line"><a id="l00135" name="l00135"></a><span class="lineno">  135</span><span class="comment"> * the transport.  Isn&#39;t this a bad requirement?  Isn&#39;t it bad to copy the entirety of the serialization?</span></div>
<div class="line"><a id="l00136" name="l00136"></a><span class="lineno">  136</span><span class="comment"> * Answer: yes, it&#39;s bad, but consider what it means to copy the *entirety* of a serialization.  Imagine a wacky</span></div>
<div class="line"><a id="l00137" name="l00137"></a><span class="lineno">  137</span><span class="comment"> * scenario where an impl of this concept leverages the file system to store the serialization on disk, since</span></div>
<div class="line"><a id="l00138" name="l00138"></a><span class="lineno">  138</span><span class="comment"> * disk has lots of storage capacity.  It would be very bad to copy the contents of the disk file into the transport</span></div>
<div class="line"><a id="l00139" name="l00139"></a><span class="lineno">  139</span><span class="comment"> * (and hence out of it, at the opposing end): it would destroy the whole point of storing on disk to begin with... but:</span></div>
<div class="line"><a id="l00140" name="l00140"></a><span class="lineno">  140</span><span class="comment"> * One could, instead of copying the *contents* of the disk file, copy the file&#39;s name into the transport</span></div>
<div class="line"><a id="l00141" name="l00141"></a><span class="lineno">  141</span><span class="comment"> * (and on the other side, read the file based on the received name).</span></div>
<div class="line"><a id="l00142" name="l00142"></a><span class="lineno">  142</span><span class="comment"> *</span></div>
<div class="line"><a id="l00143" name="l00143"></a><span class="lineno">  143</span><span class="comment"> * That is to say: The impl may (and indeed, for at least some important applications, should/must) store</span></div>
<div class="line"><a id="l00144" name="l00144"></a><span class="lineno">  144</span><span class="comment"> * the actual &quot;inner&quot; serialization (the one being mutated via mutators called on `payload_msg_builder()`) in bulk</span></div>
<div class="line"><a id="l00145" name="l00145"></a><span class="lineno">  145</span><span class="comment"> * where it wants; for example in shared memory.  emit_serialization() can/should then emit segments (ideally,</span></div>
<div class="line"><a id="l00146" name="l00146"></a><span class="lineno">  146</span><span class="comment"> * just one -- and a small one for that matter) comprised by the &quot;outer&quot; serialization, which conceptually might</span></div>
<div class="line"><a id="l00147" name="l00147"></a><span class="lineno">  147</span><span class="comment"> * be a handle referencing the (more-persistent) location of the &quot;inner&quot; (actual) serialization.  This has the</span></div>
<div class="line"><a id="l00148" name="l00148"></a><span class="lineno">  148</span><span class="comment"> * following important constraints:</span></div>
<div class="line"><a id="l00149" name="l00149"></a><span class="lineno">  149</span><span class="comment"> *   - This outer (emitted by emit_serialization()) serialization by definition must still be a capnp-`struct`.</span></div>
<div class="line"><a id="l00150" name="l00150"></a><span class="lineno">  150</span><span class="comment"> *     - The inner one, too, must still be a capnp-`struct`.</span></div>
<div class="line"><a id="l00151" name="l00151"></a><span class="lineno">  151</span><span class="comment"> *   - The inner serialization&#39;s lifetime must exceed that of `*this` to be of any use!  Otherwise the &quot;handle&quot;</span></div>
<div class="line"><a id="l00152" name="l00152"></a><span class="lineno">  152</span><span class="comment"> *     in the outer serialization will be potentially useless by the time Struct_reader counterpart tries</span></div>
<div class="line"><a id="l00153" name="l00153"></a><span class="lineno">  153</span><span class="comment"> *     to access it.</span></div>
<div class="line"><a id="l00154" name="l00154"></a><span class="lineno">  154</span><span class="comment"> *     - This requirement is no joke: obviously it&#39;s necessary; but it means one must worry about cross-process cleanup</span></div>
<div class="line"><a id="l00155" name="l00155"></a><span class="lineno">  155</span><span class="comment"> *       of the resources (such as SHM-allocated buffer(s)) used up by the inner serialization.</span></div>
<div class="line"><a id="l00156" name="l00156"></a><span class="lineno">  156</span><span class="comment"> *</span></div>
<div class="line"><a id="l00157" name="l00157"></a><span class="lineno">  157</span><span class="comment"> * To be clear, this inner-vs-outer serialization paradigm is *not* required.  It is entirely reasonable, for</span></div>
<div class="line"><a id="l00158" name="l00158"></a><span class="lineno">  158</span><span class="comment"> * some applications, to encode everything into the outer (required) serialization and not use any indirection or</span></div>
<div class="line"><a id="l00159" name="l00159"></a><span class="lineno">  159</span><span class="comment"> * inner serialization at all.  (Heap_fixed_builder -- the simplest of all -- does just that and is basically</span></div>
<div class="line"><a id="l00160" name="l00160"></a><span class="lineno">  160</span><span class="comment"> * the same as `MallocMessageBuilder`.)  The benefit is clear: there&#39;s no cross-process cleanup,</span></div>
<div class="line"><a id="l00161" name="l00161"></a><span class="lineno">  161</span><span class="comment"> * and the internal code is just much simpler.  Conversely the negative</span></div>
<div class="line"><a id="l00162" name="l00162"></a><span class="lineno">  162</span><span class="comment"> * is clear: copying large things may be expensive or even impossible (depending on the transport).</span></div>
<div class="line"><a id="l00163" name="l00163"></a><span class="lineno">  163</span><span class="comment"> *</span></div>
<div class="line"><a id="l00164" name="l00164"></a><span class="lineno">  164</span><span class="comment"> * Both have their place.  In practice, some special-use channels may use a deliberately simple schema</span></div>
<div class="line"><a id="l00165" name="l00165"></a><span class="lineno">  165</span><span class="comment"> * with small, scalar-composed payloads.  Then an outer-serialization-only impl (Heap_fixed_builder, say)</span></div>
<div class="line"><a id="l00166" name="l00166"></a><span class="lineno">  166</span><span class="comment"> * is perfect.  When this is not so, use a more complex one (typically, we think, one based on SHM; see shm::Builder).</span></div>
<div class="line"><a id="l00167" name="l00167"></a><span class="lineno">  167</span><span class="comment"> *</span></div>
<div class="line"><a id="l00168" name="l00168"></a><span class="lineno">  168</span><span class="comment"> * ### Allocation and perf ###</span></div>
<div class="line"><a id="l00169" name="l00169"></a><span class="lineno">  169</span><span class="comment"> * For this section, please assume we are dealing with a simple (outer-serialization-only/fully-copied) impl</span></div>
<div class="line"><a id="l00170" name="l00170"></a><span class="lineno">  170</span><span class="comment"> * of Struct_builder.  The most obvious impl that comes to mind is one that, each time capnp requests a</span></div>
<div class="line"><a id="l00171" name="l00171"></a><span class="lineno">  171</span><span class="comment"> * new segment of a certain minimum size, simply allocates on the regular heap.  That&#39;s what `MallocMessageBuilder`</span></div>
<div class="line"><a id="l00172" name="l00172"></a><span class="lineno">  172</span><span class="comment"> * does, and similarly Heap_fixed_builder does so as well.</span></div>
<div class="line"><a id="l00173" name="l00173"></a><span class="lineno">  173</span><span class="comment"> *</span></div>
<div class="line"><a id="l00174" name="l00174"></a><span class="lineno">  174</span><span class="comment"> * That&#39;s fine.  However, in advanced cases, it is conceivable to want more performance.  Regular-heap allocation,</span></div>
<div class="line"><a id="l00175" name="l00175"></a><span class="lineno">  175</span><span class="comment"> * depending on the size and underlying allocator impl (tcmalloc/jemalloc/ptmalloc...), can be somewhat expensive.</span></div>
<div class="line"><a id="l00176" name="l00176"></a><span class="lineno">  176</span><span class="comment"> * In avoiding heap-allocation one could use other systems: memory pools; or even just a single pre-allocated</span></div>
<div class="line"><a id="l00177" name="l00177"></a><span class="lineno">  177</span><span class="comment"> * area to be reused by *every* new `*this`.  Let&#39;s briefly think about each of those.</span></div>
<div class="line"><a id="l00178" name="l00178"></a><span class="lineno">  178</span><span class="comment"> *</span></div>
<div class="line"><a id="l00179" name="l00179"></a><span class="lineno">  179</span><span class="comment"> * Pools: This is not too different from a regular-heap allocator like Heap_fixed_builder.  It would just</span></div>
<div class="line"><a id="l00180" name="l00180"></a><span class="lineno">  180</span><span class="comment"> * allocate from (insert pool library here).  Heck, it could even use the shared-buffer functionality of a</span></div>
<div class="line"><a id="l00181" name="l00181"></a><span class="lineno">  181</span><span class="comment"> * single `flow::util::Sharing_blob` to dole out memory chunks from a single heap-allocated buffer.</span></div>
<div class="line"><a id="l00182" name="l00182"></a><span class="lineno">  182</span><span class="comment"> *</span></div>
<div class="line"><a id="l00183" name="l00183"></a><span class="lineno">  183</span><span class="comment"> * Single pre-allocated area to be reused by *every* new `*this`: This would be, of course, blindingly fast:</span></div>
<div class="line"><a id="l00184" name="l00184"></a><span class="lineno">  184</span><span class="comment"> * probably `Config` would allocate a single `Sharing_blob` and each `*this` it created would be told to use that</span></div>
<div class="line"><a id="l00185" name="l00185"></a><span class="lineno">  185</span><span class="comment"> * blob, no questions asked.  The problem, obviously, is that 2+ `*this`es might step on each other concurrently.</span></div>
<div class="line"><a id="l00186" name="l00186"></a><span class="lineno">  186</span><span class="comment"> * I.e., any use of this would basically require a pattern wherein a `*this` is created, mutated, emitted,</span></div>
<div class="line"><a id="l00187" name="l00187"></a><span class="lineno">  187</span><span class="comment"> * destroyed; *then* same for the next out-message; and so on.  Then there is no problem.  Simply put, then:</span></div>
<div class="line"><a id="l00188" name="l00188"></a><span class="lineno">  188</span><span class="comment"> * it is reasonable to develop such an impl of Struct_builder -- if one requires the user to carefully</span></div>
<div class="line"><a id="l00189" name="l00189"></a><span class="lineno">  189</span><span class="comment"> * ensure each out-message is entirely handled before work on the next one begins.  For some applications that</span></div>
<div class="line"><a id="l00190" name="l00190"></a><span class="lineno">  190</span><span class="comment"> * may be reasonable.</span></div>
<div class="line"><a id="l00191" name="l00191"></a><span class="lineno">  191</span><span class="comment"> *</span></div>
<div class="line"><a id="l00192" name="l00192"></a><span class="lineno">  192</span><span class="comment"> * Similar reasoning could be extended to 2-tier (zero-copy/SHM-based) impls of Struct_builder.  Naturally</span></div>
<div class="line"><a id="l00193" name="l00193"></a><span class="lineno">  193</span><span class="comment"> * however one would need to ensure the given payload is fully consumed by the opposing side (Struct_reader)</span></div>
<div class="line"><a id="l00194" name="l00194"></a><span class="lineno">  194</span><span class="comment"> * before creating the next `*this`; it is not enough for merely the local `*this` to be destroyed, as</span></div>
<div class="line"><a id="l00195" name="l00195"></a><span class="lineno">  195</span><span class="comment"> * the underlying payload may be referred-to by a Struct_reader still.</span></div>
<div class="line"><a id="l00196" name="l00196"></a><span class="lineno">  196</span><span class="comment"> */</span></div>
<div class="line"><a id="l00197" name="l00197"></a><span class="lineno"><a class="line" href="classipc_1_1transport_1_1struc_1_1Struct__builder.html">  197</a></span><span class="keyword">class </span><a class="code hl_class" href="classipc_1_1transport_1_1struc_1_1Struct__builder.html">Struct_builder</a> <span class="comment">// Note: movable, not copyable.</span></div>
<div class="line"><a id="l00198" name="l00198"></a><span class="lineno">  198</span>{</div>
<div class="line"><a id="l00199" name="l00199"></a><span class="lineno">  199</span><span class="keyword">public</span>:</div>
<div class="line"><a id="l00200" name="l00200"></a><span class="lineno">  200</span>  <span class="comment">// Types.</span></div>
<div class="line"><a id="l00201" name="l00201"></a><span class="lineno">  201</span><span class="comment"></span> </div>
<div class="line"><a id="l00202" name="l00202"></a><span class="lineno">  202</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00203" name="l00203"></a><span class="lineno">  203</span><span class="comment">   * Copy-ctible, copy-assignable, default-ctible type -- informally, cheaply copyable and likely an *aggregate*</span></div>
<div class="line"><a id="l00204" name="l00204"></a><span class="lineno">  204</span><span class="comment">   * `struct` -- objects of which store data that Struct_builder main ctor knows how to interpret as knobs controlling</span></div>
<div class="line"><a id="l00205" name="l00205"></a><span class="lineno">  205</span><span class="comment">   * its behavior.  While a plain-old-`struct` is a solid choice, a more complex API for a given Struct_builder impl</span></div>
<div class="line"><a id="l00206" name="l00206"></a><span class="lineno">  206</span><span class="comment">   * is conceivable.  In general, the simpler to construct and query, but especially construct (ideally by</span></div>
<div class="line"><a id="l00207" name="l00207"></a><span class="lineno">  207</span><span class="comment">   * aggregate initialization), the better.  Cheap copyability is essential.</span></div>
<div class="line"><a id="l00208" name="l00208"></a><span class="lineno">  208</span><span class="comment">   *</span></div>
<div class="line"><a id="l00209" name="l00209"></a><span class="lineno">  209</span><span class="comment">   * Internal Struct_builder impl code will be querying the knobs; the user may be explicitly constructing</span></div>
<div class="line"><a id="l00210" name="l00210"></a><span class="lineno">  210</span><span class="comment">   * Config and then constructing Struct_builder repeatedly from that same Config.  Most likely, however,</span></div>
<div class="line"><a id="l00211" name="l00211"></a><span class="lineno">  211</span><span class="comment">   * various utilities (like Session_mv::heap_fixed_builder_config()) will return ready-made `Config`s without</span></div>
<div class="line"><a id="l00212" name="l00212"></a><span class="lineno">  212</span><span class="comment">   * user&#39;s direct input.</span></div>
<div class="line"><a id="l00213" name="l00213"></a><span class="lineno">  213</span><span class="comment">   *</span></div>
<div class="line"><a id="l00214" name="l00214"></a><span class="lineno">  214</span><span class="comment">   * As you can see, there are not many requirements: this sub-concept is essentially meant to be (usually)</span></div>
<div class="line"><a id="l00215" name="l00215"></a><span class="lineno">  215</span><span class="comment">   * an aggregation of what would normally be individual ctor args to Struct_builder, a few little scalars</span></div>
<div class="line"><a id="l00216" name="l00216"></a><span class="lineno">  216</span><span class="comment">   * at that.  It *can* however conceivably feature ctors and more advanced behavior (while retaining cheap</span></div>
<div class="line"><a id="l00217" name="l00217"></a><span class="lineno">  217</span><span class="comment">   * copyability).</span></div>
<div class="line"><a id="l00218" name="l00218"></a><span class="lineno">  218</span><span class="comment">   *</span></div>
<div class="line"><a id="l00219" name="l00219"></a><span class="lineno">  219</span><span class="comment">   * While Config must default-ctible, Struct_builder may stipulate that such an as-if-default-cted</span></div>
<div class="line"><a id="l00220" name="l00220"></a><span class="lineno">  220</span><span class="comment">   * Config being passed to Struct_builder ctor = undefined behavior or otherwise invalid.</span></div>
<div class="line"><a id="l00221" name="l00221"></a><span class="lineno">  221</span><span class="comment">   */</span></div>
<div class="line"><a id="l00222" name="l00222"></a><span class="lineno"><a class="line" href="structipc_1_1transport_1_1struc_1_1Struct__builder_1_1Config.html">  222</a></span>  <span class="keyword">struct </span><a class="code hl_struct" href="structipc_1_1transport_1_1struc_1_1Struct__builder_1_1Config.html">Config</a></div>
<div class="line"><a id="l00223" name="l00223"></a><span class="lineno">  223</span>  {</div>
<div class="line"><a id="l00224" name="l00224"></a><span class="lineno">  224</span>  <span class="keyword">public</span>:</div>
<div class="line"><a id="l00225" name="l00225"></a><span class="lineno">  225</span>    <span class="comment">// Types.</span></div>
<div class="line"><a id="l00226" name="l00226"></a><span class="lineno">  226</span><span class="comment"></span> </div>
<div class="line"><a id="l00227" name="l00227"></a><span class="lineno">  227</span><span class="comment">    /// Alias to containing Struct_builder.  Useful for generic programming.</span></div>
<div class="line"><a id="l00228" name="l00228"></a><span class="lineno"><a class="line" href="structipc_1_1transport_1_1struc_1_1Struct__builder_1_1Config.html#a6abb379e5758db2691bb80cad71d6fb9">  228</a></span><span class="comment"></span>    <span class="keyword">using </span><a class="code hl_class" href="classipc_1_1transport_1_1struc_1_1Struct__builder.html">Builder</a> = <a class="code hl_function" href="classipc_1_1transport_1_1struc_1_1Struct__builder.html#a460aa187c0aaa5adfb81ecc902c7eca9">Struct_builder</a>;</div>
<div class="line"><a id="l00229" name="l00229"></a><span class="lineno">  229</span> </div>
<div class="line"><a id="l00230" name="l00230"></a><span class="lineno">  230</span>    <span class="comment">// Data.</span></div>
<div class="line"><a id="l00231" name="l00231"></a><span class="lineno">  231</span><span class="comment"></span> </div>
<div class="line"><a id="l00232" name="l00232"></a><span class="lineno">  232</span><span class="comment">    /// First knob is typically the `Logger*` (null allowed) the Struct_builder will use.</span></div>
<div class="line"><a id="l00233" name="l00233"></a><span class="lineno"><a class="line" href="structipc_1_1transport_1_1struc_1_1Struct__builder_1_1Config.html#ab818ec0d61c6c797f27222acc5fc0038">  233</a></span><span class="comment"></span>    flow::log::Logger <a class="code hl_variable" href="structipc_1_1transport_1_1struc_1_1Struct__builder_1_1Config.html#ab818ec0d61c6c797f27222acc5fc0038">m_logger_ptr</a>;</div>
<div class="line"><a id="l00234" name="l00234"></a><span class="lineno">  234</span><span class="comment"></span> </div>
<div class="line"><a id="l00235" name="l00235"></a><span class="lineno">  235</span><span class="comment">    /// An arbitrary, but cheaply-copyable in aggregate, set of knobs like (e.g.) this one follow.</span></div>
<div class="line"><a id="l00236" name="l00236"></a><span class="lineno"><a class="line" href="structipc_1_1transport_1_1struc_1_1Struct__builder_1_1Config.html#a855ec0521ca4f2a2a841d2a25ee6f12a">  236</a></span><span class="comment"></span>    Example_type <a class="code hl_variable" href="structipc_1_1transport_1_1struc_1_1Struct__builder_1_1Config.html#a855ec0521ca4f2a2a841d2a25ee6f12a">m_example_struct</a>;</div>
<div class="line"><a id="l00237" name="l00237"></a><span class="lineno">  237</span><span class="comment"></span> </div>
<div class="line"><a id="l00238" name="l00238"></a><span class="lineno">  238</span><span class="comment">    /// Or like this one.</span></div>
<div class="line"><a id="l00239" name="l00239"></a><span class="lineno"><a class="line" href="structipc_1_1transport_1_1struc_1_1Struct__builder_1_1Config.html#a267bcfe82c950040af5089543227a57e">  239</a></span><span class="comment"></span>    example_t <a class="code hl_variable" href="structipc_1_1transport_1_1struc_1_1Struct__builder_1_1Config.html#a267bcfe82c950040af5089543227a57e">m_example_val</a>;</div>
<div class="line"><a id="l00240" name="l00240"></a><span class="lineno">  240</span>  }; <span class="comment">// class Config</span></div>
<div class="line"><a id="l00241" name="l00241"></a><span class="lineno">  241</span><span class="comment"></span> </div>
<div class="line"><a id="l00242" name="l00242"></a><span class="lineno">  242</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00243" name="l00243"></a><span class="lineno">  243</span><span class="comment">   * Type objects of which specify to emit_serialization() the opposing recipient for which the serialization</span></div>
<div class="line"><a id="l00244" name="l00244"></a><span class="lineno">  244</span><span class="comment">   * is intended; Null_session if no information is necessary to specify this.  Informally: typically, in</span></div>
<div class="line"><a id="l00245" name="l00245"></a><span class="lineno">  245</span><span class="comment">   * a non-zero-copy builder the serialization itself would contain all necessary information, hence this</span></div>
<div class="line"><a id="l00246" name="l00246"></a><span class="lineno">  246</span><span class="comment">   * would be Null_session; zero-copy (SHM-based) builder needs to specify a non-empty type here.</span></div>
<div class="line"><a id="l00247" name="l00247"></a><span class="lineno">  247</span><span class="comment">   */</span></div>
<div class="line"><a id="l00248" name="l00248"></a><span class="lineno"><a class="line" href="classipc_1_1transport_1_1struc_1_1Struct__builder.html#ab90424897efed06ffc6b0884761fb31f">  248</a></span>  <span class="keyword">using </span><a class="code hl_typedef" href="classipc_1_1transport_1_1struc_1_1Struct__builder.html#ab90424897efed06ffc6b0884761fb31f">Session</a> = unspecified;</div>
<div class="line"><a id="l00249" name="l00249"></a><span class="lineno">  249</span> </div>
<div class="line"><a id="l00250" name="l00250"></a><span class="lineno">  250</span>  <span class="comment">// Constructors/destructor.</span></div>
<div class="line"><a id="l00251" name="l00251"></a><span class="lineno">  251</span><span class="comment"></span> </div>
<div class="line"><a id="l00252" name="l00252"></a><span class="lineno">  252</span><span class="comment">  /// Default ctor, leaving `*this` in a state only suitable for destruction or being moved-to.</span></div>
<div class="line"><a id="l00253" name="l00253"></a><span class="lineno"><a class="line" href="classipc_1_1transport_1_1struc_1_1Struct__builder.html#a460aa187c0aaa5adfb81ecc902c7eca9">  253</a></span><span class="comment"></span>  <a class="code hl_function" href="classipc_1_1transport_1_1struc_1_1Struct__builder.html#a460aa187c0aaa5adfb81ecc902c7eca9">Struct_builder</a>();</div>
<div class="line"><a id="l00254" name="l00254"></a><span class="lineno">  254</span><span class="comment"></span> </div>
<div class="line"><a id="l00255" name="l00255"></a><span class="lineno">  255</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00256" name="l00256"></a><span class="lineno">  256</span><span class="comment">   * Main ctor, creating a new builder according to the knobs in `Config config` arg.</span></div>
<div class="line"><a id="l00257" name="l00257"></a><span class="lineno">  257</span><span class="comment">   *</span></div>
<div class="line"><a id="l00258" name="l00258"></a><span class="lineno">  258</span><span class="comment">   * @param config</span></div>
<div class="line"><a id="l00259" name="l00259"></a><span class="lineno">  259</span><span class="comment">   *        Struct_builder::Config storing the knobs controlling how `*this` will work.</span></div>
<div class="line"><a id="l00260" name="l00260"></a><span class="lineno">  260</span><span class="comment">   */</span></div>
<div class="line"><a id="l00261" name="l00261"></a><span class="lineno"><a class="line" href="classipc_1_1transport_1_1struc_1_1Struct__builder.html#ad98eba0fc5a8b377253eac797a9a117e">  261</a></span>  <span class="keyword">explicit</span> <a class="code hl_function" href="classipc_1_1transport_1_1struc_1_1Struct__builder.html#ad98eba0fc5a8b377253eac797a9a117e">Struct_builder</a>(<span class="keyword">const</span> <a class="code hl_struct" href="structipc_1_1transport_1_1struc_1_1Struct__builder_1_1Config.html">Config</a>&amp; config)</div>
<div class="line"><a id="l00262" name="l00262"></a><span class="lineno">  262</span> </div>
<div class="line"><a id="l00263" name="l00263"></a><span class="lineno">  263</span>  <span class="comment">/// Disallow copy construction.</span></div>
<div class="line"><a id="l00264" name="l00264"></a><span class="lineno">  264</span>  <a class="code hl_function" href="classipc_1_1transport_1_1struc_1_1Struct__builder.html#a460aa187c0aaa5adfb81ecc902c7eca9">Struct_builder</a>(<span class="keyword">const</span> <a class="code hl_class" href="classipc_1_1transport_1_1struc_1_1Struct__builder.html">Struct_builder</a>&amp;) = <span class="keyword">delete</span>;</div>
<div class="line"><a id="l00265" name="l00265"></a><span class="lineno">  265</span><span class="comment"></span> </div>
<div class="line"><a id="l00266" name="l00266"></a><span class="lineno">  266</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00267" name="l00267"></a><span class="lineno">  267</span><span class="comment">   * Move-constructs `*this` to be equal to `src`, while `src` becomes as-if defaulted-cted.</span></div>
<div class="line"><a id="l00268" name="l00268"></a><span class="lineno">  268</span><span class="comment">   *</span></div>
<div class="line"><a id="l00269" name="l00269"></a><span class="lineno">  269</span><span class="comment">   * @param src</span></div>
<div class="line"><a id="l00270" name="l00270"></a><span class="lineno">  270</span><span class="comment">   *        Moved-from object that becomes as-if default-cted.</span></div>
<div class="line"><a id="l00271" name="l00271"></a><span class="lineno">  271</span><span class="comment">   */</span></div>
<div class="line"><a id="l00272" name="l00272"></a><span class="lineno"><a class="line" href="classipc_1_1transport_1_1struc_1_1Struct__builder.html#a2c413c604b1d6abf63ce1589367dd772">  272</a></span>  <a class="code hl_function" href="classipc_1_1transport_1_1struc_1_1Struct__builder.html#a2c413c604b1d6abf63ce1589367dd772">Struct_builder</a>(<a class="code hl_class" href="classipc_1_1transport_1_1struc_1_1Struct__builder.html">Struct_builder</a>&amp;&amp; src);</div>
<div class="line"><a id="l00273" name="l00273"></a><span class="lineno">  273</span><span class="comment"></span> </div>
<div class="line"><a id="l00274" name="l00274"></a><span class="lineno">  274</span><span class="comment">  /// Destructor.  Do not use `*payload_msg_builder()` or any copies thereof past this.</span></div>
<div class="line"><a id="l00275" name="l00275"></a><span class="lineno"><a class="line" href="classipc_1_1transport_1_1struc_1_1Struct__builder.html#a008f6b6456a4b2dab63cdda5f9e4cfe5">  275</a></span><span class="comment"></span>  <a class="code hl_function" href="classipc_1_1transport_1_1struc_1_1Struct__builder.html#a008f6b6456a4b2dab63cdda5f9e4cfe5">~Struct_builder</a>();</div>
<div class="line"><a id="l00276" name="l00276"></a><span class="lineno">  276</span> </div>
<div class="line"><a id="l00277" name="l00277"></a><span class="lineno">  277</span>  <span class="comment">// Methods.</span></div>
<div class="line"><a id="l00278" name="l00278"></a><span class="lineno">  278</span><span class="comment"></span> </div>
<div class="line"><a id="l00279" name="l00279"></a><span class="lineno">  279</span><span class="comment">  /// Disallow copy assignment.</span></div>
<div class="line"><a id="l00280" name="l00280"></a><span class="lineno"><a class="line" href="classipc_1_1transport_1_1struc_1_1Struct__builder.html#a1899e36ae85a208f3208adfaeb5f0000">  280</a></span><span class="comment"></span>  <a class="code hl_class" href="classipc_1_1transport_1_1struc_1_1Struct__builder.html">Struct_builder</a>&amp; <a class="code hl_function" href="classipc_1_1transport_1_1struc_1_1Struct__builder.html#a1899e36ae85a208f3208adfaeb5f0000">operator=</a>(<span class="keyword">const</span> <a class="code hl_class" href="classipc_1_1transport_1_1struc_1_1Struct__builder.html">Struct_builder</a>&amp;) = <span class="keyword">delete</span>;</div>
<div class="line"><a id="l00281" name="l00281"></a><span class="lineno">  281</span><span class="comment"></span> </div>
<div class="line"><a id="l00282" name="l00282"></a><span class="lineno">  282</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00283" name="l00283"></a><span class="lineno">  283</span><span class="comment">   * Move-assigns `*this` to be equal to `src`, while `src` becomes as-if defaulted-cted; or no-op</span></div>
<div class="line"><a id="l00284" name="l00284"></a><span class="lineno">  284</span><span class="comment">   * if `&amp;src == this`.</span></div>
<div class="line"><a id="l00285" name="l00285"></a><span class="lineno">  285</span><span class="comment">   *</span></div>
<div class="line"><a id="l00286" name="l00286"></a><span class="lineno">  286</span><span class="comment">   * @param src</span></div>
<div class="line"><a id="l00287" name="l00287"></a><span class="lineno">  287</span><span class="comment">   *        Moved-from object that becomes as-if default-cted, unless it is `*this`.</span></div>
<div class="line"><a id="l00288" name="l00288"></a><span class="lineno">  288</span><span class="comment">   * @return `*this`.</span></div>
<div class="line"><a id="l00289" name="l00289"></a><span class="lineno">  289</span><span class="comment">   */</span></div>
<div class="line"><a id="l00290" name="l00290"></a><span class="lineno"><a class="line" href="classipc_1_1transport_1_1struc_1_1Struct__builder.html#a708a66e9598c75a1f54828a4805da4f0">  290</a></span>  <a class="code hl_class" href="classipc_1_1transport_1_1struc_1_1Struct__builder.html">Struct_builder</a>&amp; <a class="code hl_function" href="classipc_1_1transport_1_1struc_1_1Struct__builder.html#a708a66e9598c75a1f54828a4805da4f0">operator=</a>(<a class="code hl_class" href="classipc_1_1transport_1_1struc_1_1Struct__builder.html">Struct_builder</a>&amp;&amp; src);</div>
<div class="line"><a id="l00291" name="l00291"></a><span class="lineno">  291</span><span class="comment"></span> </div>
<div class="line"><a id="l00292" name="l00292"></a><span class="lineno">  292</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00293" name="l00293"></a><span class="lineno">  293</span><span class="comment">   * Pointer to the payload #Capnp_msg_builder_interface, suitable for mutation by the user.  Informally: we expect the</span></div>
<div class="line"><a id="l00294" name="l00294"></a><span class="lineno">  294</span><span class="comment">   * outside use of some subset of the pointee methods `initRoot()`, `getRoot()`, `setRoot()`, `adoptRoot()`,</span></div>
<div class="line"><a id="l00295" name="l00295"></a><span class="lineno">  295</span><span class="comment">   * `getOrphanage()` but *not* `getSegmentsForOutput()`.  To access the serialization properly you must use</span></div>
<div class="line"><a id="l00296" name="l00296"></a><span class="lineno">  296</span><span class="comment">   * emit_serialization() instead.  Otherwise you&#39;d be foregoing the main point of Struct_builder&#39;s existence which</span></div>
<div class="line"><a id="l00297" name="l00297"></a><span class="lineno">  297</span><span class="comment">   * is to allow for a 2-tier serialization (as described in the concept doc header) and therefore true zero-copy</span></div>
<div class="line"><a id="l00298" name="l00298"></a><span class="lineno">  298</span><span class="comment">   * end-to-end.</span></div>
<div class="line"><a id="l00299" name="l00299"></a><span class="lineno">  299</span><span class="comment">   *</span></div>
<div class="line"><a id="l00300" name="l00300"></a><span class="lineno">  300</span><span class="comment">   * ### Errors ###</span></div>
<div class="line"><a id="l00301" name="l00301"></a><span class="lineno">  301</span><span class="comment">   * See emit_serialization().</span></div>
<div class="line"><a id="l00302" name="l00302"></a><span class="lineno">  302</span><span class="comment">   *</span></div>
<div class="line"><a id="l00303" name="l00303"></a><span class="lineno">  303</span><span class="comment">   * @return See above.  Always returns the same pointer.</span></div>
<div class="line"><a id="l00304" name="l00304"></a><span class="lineno">  304</span><span class="comment">   */</span></div>
<div class="line"><a id="l00305" name="l00305"></a><span class="lineno"><a class="line" href="classipc_1_1transport_1_1struc_1_1Struct__builder.html#a9a4b9587c162f85ad4d3e0a5fad8dffb">  305</a></span>  <a class="code hl_class" href="classCapnp__msg__builder__interface.html">Capnp_msg_builder_interface</a>* <a class="code hl_function" href="classipc_1_1transport_1_1struc_1_1Struct__builder.html#a9a4b9587c162f85ad4d3e0a5fad8dffb">payload_msg_builder</a>();</div>
<div class="line"><a id="l00306" name="l00306"></a><span class="lineno">  306</span><span class="comment"></span> </div>
<div class="line"><a id="l00307" name="l00307"></a><span class="lineno">  307</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00308" name="l00308"></a><span class="lineno">  308</span><span class="comment">   * Returns the serialization in the form of a sequence of 1+ pointers to `Blob`s which are guaranteed to remain</span></div>
<div class="line"><a id="l00309" name="l00309"></a><span class="lineno">  309</span><span class="comment">   * valid and unchanged until `*this` is destroyed, or the contents are further mutated via payload_msg_builder().</span></div>
<div class="line"><a id="l00310" name="l00310"></a><span class="lineno">  310</span><span class="comment">   * These are *appended* to `*target_blobs`.</span></div>
<div class="line"><a id="l00311" name="l00311"></a><span class="lineno">  311</span><span class="comment">   *</span></div>
<div class="line"><a id="l00312" name="l00312"></a><span class="lineno">  312</span><span class="comment">   * You may call this method more than once per `*this`.  However, if it fails, `*this` shall be considered useless.</span></div>
<div class="line"><a id="l00313" name="l00313"></a><span class="lineno">  313</span><span class="comment">   * Please read the concept doc header carefully regarding the context and proper use of calling</span></div>
<div class="line"><a id="l00314" name="l00314"></a><span class="lineno">  314</span><span class="comment">   * emit_serialization() more than once.</span></div>
<div class="line"><a id="l00315" name="l00315"></a><span class="lineno">  315</span><span class="comment">   *</span></div>
<div class="line"><a id="l00316" name="l00316"></a><span class="lineno">  316</span><span class="comment">   * The result (`*target_blobs` contents) is (generally) meaningless once `*this` is mutated further.</span></div>
<div class="line"><a id="l00317" name="l00317"></a><span class="lineno">  317</span><span class="comment">   *</span></div>
<div class="line"><a id="l00318" name="l00318"></a><span class="lineno">  318</span><span class="comment">   * ### Errors ###</span></div>
<div class="line"><a id="l00319" name="l00319"></a><span class="lineno">  319</span><span class="comment">   * emit_serialization() may emit an error via standard (to Flow-IPC) semantics if the serialization procedure in</span></div>
<div class="line"><a id="l00320" name="l00320"></a><span class="lineno">  320</span><span class="comment">   * some way fails.  Mutations on payload_msg_builder() shall be assumed to work and not throw or otherwise emit</span></div>
<div class="line"><a id="l00321" name="l00321"></a><span class="lineno">  321</span><span class="comment">   * errors, outside of misuse of capnp or bugs in capnp.  However emit_serialization() may report an error</span></div>
<div class="line"><a id="l00322" name="l00322"></a><span class="lineno">  322</span><span class="comment">   * synchronously, even if internally it is known there is an error earlier than the emit_serialization() call itself.</span></div>
<div class="line"><a id="l00323" name="l00323"></a><span class="lineno">  323</span><span class="comment">   *</span></div>
<div class="line"><a id="l00324" name="l00324"></a><span class="lineno">  324</span><span class="comment">   * @param target_blobs</span></div>
<div class="line"><a id="l00325" name="l00325"></a><span class="lineno">  325</span><span class="comment">   *        On success (no error emitted) this is appended-to with the sequence of pointers to segments</span></div>
<div class="line"><a id="l00326" name="l00326"></a><span class="lineno">  326</span><span class="comment">   *        as `Blob`s.</span></div>
<div class="line"><a id="l00327" name="l00327"></a><span class="lineno">  327</span><span class="comment">   * @param session</span></div>
<div class="line"><a id="l00328" name="l00328"></a><span class="lineno">  328</span><span class="comment">   *        Specifies the opposing recipient for which the serialization is intended.</span></div>
<div class="line"><a id="l00329" name="l00329"></a><span class="lineno">  329</span><span class="comment">   *        If #Session is Null_session, then `Session()` is the only value to supply here.  Otherwise more</span></div>
<div class="line"><a id="l00330" name="l00330"></a><span class="lineno">  330</span><span class="comment">   *        information is necessary.</span></div>
<div class="line"><a id="l00331" name="l00331"></a><span class="lineno">  331</span><span class="comment">   * @param err_code</span></div>
<div class="line"><a id="l00332" name="l00332"></a><span class="lineno">  332</span><span class="comment">   *        See `flow::Error_code` docs for error reporting semantics.</span></div>
<div class="line"><a id="l00333" name="l00333"></a><span class="lineno">  333</span><span class="comment">   */</span></div>
<div class="line"><a id="l00334" name="l00334"></a><span class="lineno"><a class="line" href="classipc_1_1transport_1_1struc_1_1Struct__builder.html#af5085934123f075c6d0701e9e45e4bcc">  334</a></span>  <span class="keywordtype">void</span> <a class="code hl_function" href="classipc_1_1transport_1_1struc_1_1Struct__builder.html#af5085934123f075c6d0701e9e45e4bcc">emit_serialization</a>(<a class="code hl_typedef" href="namespaceipc_1_1transport_1_1struc.html#a82a69eaa39cbe8a002de1266f1cbb5cb">Segment_ptrs</a>* target_blobs, <span class="keyword">const</span> <a class="code hl_typedef" href="classipc_1_1transport_1_1struc_1_1Struct__builder.html#ab90424897efed06ffc6b0884761fb31f">Session</a>&amp; session, <a class="code hl_typedef" href="namespaceipc.html#aa3192e586cc45d3e7c22463bf2760f89">Error_code</a>* err_code = 0) <span class="keyword">const</span>;</div>
<div class="line"><a id="l00335" name="l00335"></a><span class="lineno">  335</span><span class="comment"></span> </div>
<div class="line"><a id="l00336" name="l00336"></a><span class="lineno">  336</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00337" name="l00337"></a><span class="lineno">  337</span><span class="comment">   * Returns what `target_blobs.size()` would return after calling `emit_serialization(&amp;target_blobs)` (with</span></div>
<div class="line"><a id="l00338" name="l00338"></a><span class="lineno">  338</span><span class="comment">   * an empty `target_blobs` going-in), right now.</span></div>
<div class="line"><a id="l00339" name="l00339"></a><span class="lineno">  339</span><span class="comment">   *</span></div>
<div class="line"><a id="l00340" name="l00340"></a><span class="lineno">  340</span><span class="comment">   * @return See above.</span></div>
<div class="line"><a id="l00341" name="l00341"></a><span class="lineno">  341</span><span class="comment">   */</span></div>
<div class="line"><a id="l00342" name="l00342"></a><span class="lineno"><a class="line" href="classipc_1_1transport_1_1struc_1_1Struct__builder.html#ae1516b0d68c48f2e13baf6aca366ac6c">  342</a></span>  <span class="keywordtype">size_t</span> <a class="code hl_function" href="classipc_1_1transport_1_1struc_1_1Struct__builder.html#ae1516b0d68c48f2e13baf6aca366ac6c">n_serialization_segments</a>() <span class="keyword">const</span>;</div>
<div class="line"><a id="l00343" name="l00343"></a><span class="lineno">  343</span>}; <span class="comment">// class Struct_builder</span></div>
<div class="line"><a id="l00344" name="l00344"></a><span class="lineno">  344</span><span class="comment"></span> </div>
<div class="line"><a id="l00345" name="l00345"></a><span class="lineno">  345</span><span class="comment">/**</span></div>
<div class="line"><a id="l00346" name="l00346"></a><span class="lineno">  346</span><span class="comment"> * A documentation-only *concept* that is, conceptually, roughly what `capnp::MessageReader` is to</span></div>
<div class="line"><a id="l00347" name="l00347"></a><span class="lineno">  347</span><span class="comment"> * `capnp::MessageBuilder`, to be used on an in-message serialized by a counterpart</span></div>
<div class="line"><a id="l00348" name="l00348"></a><span class="lineno">  348</span><span class="comment"> * Struct_builder, having been transmitted over an IPC transmitter of blobs.  The following discussion assumes</span></div>
<div class="line"><a id="l00349" name="l00349"></a><span class="lineno">  349</span><span class="comment"> * understanding of Struct_builder (see its doc header).</span></div>
<div class="line"><a id="l00350" name="l00350"></a><span class="lineno">  350</span><span class="comment"> *</span></div>
<div class="line"><a id="l00351" name="l00351"></a><span class="lineno">  351</span><span class="comment"> * @see Struct_builder, the counterpart concept.</span></div>
<div class="line"><a id="l00352" name="l00352"></a><span class="lineno">  352</span><span class="comment"> *</span></div>
<div class="line"><a id="l00353" name="l00353"></a><span class="lineno">  353</span><span class="comment"> * Here is how a Struct_reader is used (in order):</span></div>
<div class="line"><a id="l00354" name="l00354"></a><span class="lineno">  354</span><span class="comment"> *   - Suppose the counterpart Struct_builder was used as documented in its doc header, for a given out-message.</span></div>
<div class="line"><a id="l00355" name="l00355"></a><span class="lineno">  355</span><span class="comment"> *   - Construct a matching Struct_reader on the other side.</span></div>
<div class="line"><a id="l00356" name="l00356"></a><span class="lineno">  356</span><span class="comment"> *     - See also Struct_reader::Config.</span></div>
<div class="line"><a id="l00357" name="l00357"></a><span class="lineno">  357</span><span class="comment"> *   - Call `add_serialization_segment(M)`, where M is the maximum number of bytes the next blob-read out of the</span></div>
<div class="line"><a id="l00358" name="l00358"></a><span class="lineno">  358</span><span class="comment"> *     transport might return when reading the next serialization segment produced by Struct_builder.</span></div>
<div class="line"><a id="l00359" name="l00359"></a><span class="lineno">  359</span><span class="comment"> *     (M, in practice, is limited by at least the transport and how it is used; and the segment sizes</span></div>
<div class="line"><a id="l00360" name="l00360"></a><span class="lineno">  360</span><span class="comment"> *     the Struct_builder impl in practice produces.)</span></div>
<div class="line"><a id="l00361" name="l00361"></a><span class="lineno">  361</span><span class="comment"> *     - `*this` shall obtain an area in memory at least M bytes long into which it is guaranteed safe for</span></div>
<div class="line"><a id="l00362" name="l00362"></a><span class="lineno">  362</span><span class="comment"> *       for the user to direct-write, until the next add_serialization_segment(), deserialization(), or dtor</span></div>
<div class="line"><a id="l00363" name="l00363"></a><span class="lineno">  363</span><span class="comment"> *       call (whichever happens earliest).</span></div>
<div class="line"><a id="l00364" name="l00364"></a><span class="lineno">  364</span><span class="comment"> *     - add_serialization_segment() shall return a *pointer* to a `flow::util::Blob` whose</span></div>
<div class="line"><a id="l00365" name="l00365"></a><span class="lineno">  365</span><span class="comment"> *       [`begin()`, `end()`) range represents that memory area (with `.size()` equal to M).</span></div>
<div class="line"><a id="l00366" name="l00366"></a><span class="lineno">  366</span><span class="comment"> *       - If the impl determines that its (not specified by this concept) memory acquisition algorithm</span></div>
<div class="line"><a id="l00367" name="l00367"></a><span class="lineno">  367</span><span class="comment"> *         is incapable of obtaining M bytes, it shall return null.  The user must be ready for this</span></div>
<div class="line"><a id="l00368" name="l00368"></a><span class="lineno">  368</span><span class="comment"> *         eventuality.</span></div>
<div class="line"><a id="l00369" name="l00369"></a><span class="lineno">  369</span><span class="comment"> *   - Copy the next segment&#39;s contents out of the transport into the aforementioned `Blob`.</span></div>
<div class="line"><a id="l00370" name="l00370"></a><span class="lineno">  370</span><span class="comment"> *   - Use `flow::util::Blob::resize()` (or similar methods that invoke it, notably `start_past_prefix_inc()`)</span></div>
<div class="line"><a id="l00371" name="l00371"></a><span class="lineno">  371</span><span class="comment"> *     to modify the [`begin()`, `end()`) range such that it stores the exact contents of the segment.</span></div>
<div class="line"><a id="l00372" name="l00372"></a><span class="lineno">  372</span><span class="comment"> *     - In practice: It at least means `resize(K)`, where `K &lt;= M`, to mark the actual size of the received</span></div>
<div class="line"><a id="l00373" name="l00373"></a><span class="lineno">  373</span><span class="comment"> *       segment, since M is the *max* possible size.  So the garbage area into which no bytes were written must</span></div>
<div class="line"><a id="l00374" name="l00374"></a><span class="lineno">  374</span><span class="comment"> *       be excluded.</span></div>
<div class="line"><a id="l00375" name="l00375"></a><span class="lineno">  375</span><span class="comment"> *     - It may also mean sliding around `begin()` and/or `end()` to deliberately exclude any framing information</span></div>
<div class="line"><a id="l00376" name="l00376"></a><span class="lineno">  376</span><span class="comment"> *       used by the user&#39;s protocol when transmitting segments.  This is important to maintain zero-copy perf.</span></div>
<div class="line"><a id="l00377" name="l00377"></a><span class="lineno">  377</span><span class="comment"> *     - Behavior is undefined if the user calls `.make_zero()` on that blob.  Only `.resize()` (and its</span></div>
<div class="line"><a id="l00378" name="l00378"></a><span class="lineno">  378</span><span class="comment"> *       convenience wrappers like `start_past_prefix_inc()`) may be invoked.</span></div>
<div class="line"><a id="l00379" name="l00379"></a><span class="lineno">  379</span><span class="comment"> *   - If and only if the serialization produced by the Struct_builder consists of 2+ segments:</span></div>
<div class="line"><a id="l00380" name="l00380"></a><span class="lineno">  380</span><span class="comment"> *     Repeat the previous 3 bullet points, in order, for each of the additional 1+ segments.</span></div>
<div class="line"><a id="l00381" name="l00381"></a><span class="lineno">  381</span><span class="comment"> *   - Lastly execute Struct_reader::deserialization&lt;Struct&gt;() (at most once) to obtain obtain a capnp-generated</span></div>
<div class="line"><a id="l00382" name="l00382"></a><span class="lineno">  382</span><span class="comment"> *     `Struct::Reader`.</span></div>
<div class="line"><a id="l00383" name="l00383"></a><span class="lineno">  383</span><span class="comment"> *     - Access the structured contents that the other side had mutated-in via the latter-returned `Struct::Reader`.</span></div>
<div class="line"><a id="l00384" name="l00384"></a><span class="lineno">  384</span><span class="comment"> *   - Finally, the Struct_reader `*this` can be destroyed.</span></div>
<div class="line"><a id="l00385" name="l00385"></a><span class="lineno">  385</span><span class="comment"> *</span></div>
<div class="line"><a id="l00386" name="l00386"></a><span class="lineno">  386</span><span class="comment"> * ### Copying versus zero-copy ###</span></div>
<div class="line"><a id="l00387" name="l00387"></a><span class="lineno">  387</span><span class="comment"> * See the same-named section of Struct_builder doc header.  Similar concerns apply here.  Generally speaking,</span></div>
<div class="line"><a id="l00388" name="l00388"></a><span class="lineno">  388</span><span class="comment"> * how a Struct_reader works is dictated by the decisions made for its Struct_builder counterpart.</span></div>
<div class="line"><a id="l00389" name="l00389"></a><span class="lineno">  389</span><span class="comment"> *</span></div>
<div class="line"><a id="l00390" name="l00390"></a><span class="lineno">  390</span><span class="comment"> * ### Allocation and perf ###</span></div>
<div class="line"><a id="l00391" name="l00391"></a><span class="lineno">  391</span><span class="comment"> * See the same-named section of Struct_builder doc header first.  Similar concerns apply here, but</span></div>
<div class="line"><a id="l00392" name="l00392"></a><span class="lineno">  392</span><span class="comment"> * actually the decision about how to obtain memory areas as returned by add_serialization_segment() in</span></div>
<div class="line"><a id="l00393" name="l00393"></a><span class="lineno">  393</span><span class="comment"> * Struct_reader can be 100% decoupled from how Struct_builder counterpart acquires memory.</span></div>
<div class="line"><a id="l00394" name="l00394"></a><span class="lineno">  394</span><span class="comment"> * E.g., the builder might allocate from heap, while the reader might allocate from a single</span></div>
<div class="line"><a id="l00395" name="l00395"></a><span class="lineno">  395</span><span class="comment"> * buffer allocated by `Config`, just because the latter has a single-threaded receiver setup, while the former</span></div>
<div class="line"><a id="l00396" name="l00396"></a><span class="lineno">  396</span><span class="comment"> * involves multi-threaded concurrently-sending chaos.  One can mix and match: the outer serialization is</span></div>
<div class="line"><a id="l00397" name="l00397"></a><span class="lineno">  397</span><span class="comment"> * always copied-into the transport (then destroyed) on the builder side and copied-from the transport</span></div>
<div class="line"><a id="l00398" name="l00398"></a><span class="lineno">  398</span><span class="comment"> * on the reader side.  The manner in which memory is acquired before each write (builder case)</span></div>
<div class="line"><a id="l00399" name="l00399"></a><span class="lineno">  399</span><span class="comment"> * or before each read (reader case) can be determined by the algorithm used by the application on each</span></div>
<div class="line"><a id="l00400" name="l00400"></a><span class="lineno">  400</span><span class="comment"> * side.</span></div>
<div class="line"><a id="l00401" name="l00401"></a><span class="lineno">  401</span><span class="comment"> *</span></div>
<div class="line"><a id="l00402" name="l00402"></a><span class="lineno">  402</span><span class="comment"> * ### Why is add_serialization_segment() designed this way? ###</span></div>
<div class="line"><a id="l00403" name="l00403"></a><span class="lineno">  403</span><span class="comment"> * It might seem unnecessarily complex: user must call add_serialization_segment(), then write to that `Blob`</span></div>
<div class="line"><a id="l00404" name="l00404"></a><span class="lineno">  404</span><span class="comment"> * and adjust its range.  They could conceivably just allocate their own `Blob` and then `move()` it into</span></div>
<div class="line"><a id="l00405" name="l00405"></a><span class="lineno">  405</span><span class="comment"> * `*this` via a single, simpler `add_serialization_segment(Blob&amp;&amp;)` call.  So why is it done the former way?</span></div>
<div class="line"><a id="l00406" name="l00406"></a><span class="lineno">  406</span><span class="comment"> *</span></div>
<div class="line"><a id="l00407" name="l00407"></a><span class="lineno">  407</span><span class="comment"> * Answer: It&#39;s to support the possibilities discussed in the &quot;Allocation and perf&quot; section above.</span></div>
<div class="line"><a id="l00408" name="l00408"></a><span class="lineno">  408</span><span class="comment"> * add_serialization_segment() places the responsibility of obtaining target memory for the blob-read</span></div>
<div class="line"><a id="l00409" name="l00409"></a><span class="lineno">  409</span><span class="comment"> * on the Struct_reader concept impl.  Hence different concept impls can be swapped in for different</span></div>
<div class="line"><a id="l00410" name="l00410"></a><span class="lineno">  410</span><span class="comment"> * perf/use-case trade-offs.  One would use a pool -- another would use the heap... etc.</span></div>
<div class="line"><a id="l00411" name="l00411"></a><span class="lineno">  411</span><span class="comment"> */</span></div>
<div class="line"><a id="l00412" name="l00412"></a><span class="lineno"><a class="line" href="classipc_1_1transport_1_1struc_1_1Struct__reader.html">  412</a></span><span class="keyword">class </span><a class="code hl_class" href="classipc_1_1transport_1_1struc_1_1Struct__reader.html">Struct_reader</a> <span class="comment">// Note: movable, not copyable.</span></div>
<div class="line"><a id="l00413" name="l00413"></a><span class="lineno">  413</span>{</div>
<div class="line"><a id="l00414" name="l00414"></a><span class="lineno">  414</span><span class="keyword">public</span>:</div>
<div class="line"><a id="l00415" name="l00415"></a><span class="lineno">  415</span>  <span class="comment">// Types.</span></div>
<div class="line"><a id="l00416" name="l00416"></a><span class="lineno">  416</span><span class="comment"></span> </div>
<div class="line"><a id="l00417" name="l00417"></a><span class="lineno">  417</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00418" name="l00418"></a><span class="lineno">  418</span><span class="comment">   * Analogous to Struct_builder::Config but for deserialization.</span></div>
<div class="line"><a id="l00419" name="l00419"></a><span class="lineno">  419</span><span class="comment">   * @see Struct_builder::Config</span></div>
<div class="line"><a id="l00420" name="l00420"></a><span class="lineno">  420</span><span class="comment">   */</span></div>
<div class="line"><a id="l00421" name="l00421"></a><span class="lineno"><a class="line" href="structipc_1_1transport_1_1struc_1_1Struct__reader_1_1Config.html">  421</a></span>  <span class="keyword">struct </span><a class="code hl_struct" href="structipc_1_1transport_1_1struc_1_1Struct__reader_1_1Config.html">Config</a></div>
<div class="line"><a id="l00422" name="l00422"></a><span class="lineno">  422</span>  {</div>
<div class="line"><a id="l00423" name="l00423"></a><span class="lineno">  423</span>  <span class="keyword">public</span>:</div>
<div class="line"><a id="l00424" name="l00424"></a><span class="lineno">  424</span>    <span class="comment">// Types.</span></div>
<div class="line"><a id="l00425" name="l00425"></a><span class="lineno">  425</span><span class="comment"></span> </div>
<div class="line"><a id="l00426" name="l00426"></a><span class="lineno">  426</span><span class="comment">    /// Alias to containing Struct_reader.  Useful for generic programming.</span></div>
<div class="line"><a id="l00427" name="l00427"></a><span class="lineno"><a class="line" href="structipc_1_1transport_1_1struc_1_1Struct__reader_1_1Config.html#a8b31bcbb6f8db3370aa664eb95cddfb8">  427</a></span><span class="comment"></span>    <span class="keyword">using </span><a class="code hl_class" href="classipc_1_1transport_1_1struc_1_1Struct__reader.html">Reader</a> = <a class="code hl_function" href="classipc_1_1transport_1_1struc_1_1Struct__reader.html#a4dc980273439330d6d2359e764c7680a">Struct_reader</a>;</div>
<div class="line"><a id="l00428" name="l00428"></a><span class="lineno">  428</span> </div>
<div class="line"><a id="l00429" name="l00429"></a><span class="lineno">  429</span>    <span class="comment">// Data.</span></div>
<div class="line"><a id="l00430" name="l00430"></a><span class="lineno">  430</span><span class="comment"></span> </div>
<div class="line"><a id="l00431" name="l00431"></a><span class="lineno">  431</span><span class="comment">    /// First knob is typically the `Logger*` (null allowed) the Struct_reader will use.</span></div>
<div class="line"><a id="l00432" name="l00432"></a><span class="lineno"><a class="line" href="structipc_1_1transport_1_1struc_1_1Struct__reader_1_1Config.html#aee7630fa3413e39c1cec5f544ca0d8fe">  432</a></span><span class="comment"></span>    flow::log::Logger <a class="code hl_variable" href="structipc_1_1transport_1_1struc_1_1Struct__reader_1_1Config.html#aee7630fa3413e39c1cec5f544ca0d8fe">m_logger_ptr</a>;</div>
<div class="line"><a id="l00433" name="l00433"></a><span class="lineno">  433</span><span class="comment"></span> </div>
<div class="line"><a id="l00434" name="l00434"></a><span class="lineno">  434</span><span class="comment">    /// An arbitrary, but cheaply-copyable in aggregate, set of knobs like (e.g.) this one follow.</span></div>
<div class="line"><a id="l00435" name="l00435"></a><span class="lineno"><a class="line" href="structipc_1_1transport_1_1struc_1_1Struct__reader_1_1Config.html#af3ab43e46bbae80b337a756e3e7083f1">  435</a></span><span class="comment"></span>    Example_type <a class="code hl_variable" href="structipc_1_1transport_1_1struc_1_1Struct__reader_1_1Config.html#af3ab43e46bbae80b337a756e3e7083f1">m_example_struct</a>;</div>
<div class="line"><a id="l00436" name="l00436"></a><span class="lineno">  436</span><span class="comment"></span> </div>
<div class="line"><a id="l00437" name="l00437"></a><span class="lineno">  437</span><span class="comment">    /// Or yet another!  Note in no way are these necessarily symmetric to Struct_builder::Config counterpart.</span></div>
<div class="line"><a id="l00438" name="l00438"></a><span class="lineno"><a class="line" href="structipc_1_1transport_1_1struc_1_1Struct__reader_1_1Config.html#aab19f05acc30438dc887aaaa6ff8ae27">  438</a></span><span class="comment"></span>    example_t <a class="code hl_variable" href="structipc_1_1transport_1_1struc_1_1Struct__reader_1_1Config.html#aab19f05acc30438dc887aaaa6ff8ae27">m_example_val</a>;</div>
<div class="line"><a id="l00439" name="l00439"></a><span class="lineno">  439</span>  }; <span class="comment">// struct Config</span></div>
<div class="line"><a id="l00440" name="l00440"></a><span class="lineno">  440</span> </div>
<div class="line"><a id="l00441" name="l00441"></a><span class="lineno">  441</span>  <span class="comment">// Constructors/destructor.</span></div>
<div class="line"><a id="l00442" name="l00442"></a><span class="lineno">  442</span><span class="comment"></span> </div>
<div class="line"><a id="l00443" name="l00443"></a><span class="lineno">  443</span><span class="comment">  /// Default ctor, leaving `*this` in a state only suitable for destruction or being moved-to.</span></div>
<div class="line"><a id="l00444" name="l00444"></a><span class="lineno"><a class="line" href="classipc_1_1transport_1_1struc_1_1Struct__reader.html#a4dc980273439330d6d2359e764c7680a">  444</a></span><span class="comment"></span>  <a class="code hl_function" href="classipc_1_1transport_1_1struc_1_1Struct__reader.html#a4dc980273439330d6d2359e764c7680a">Struct_reader</a>();</div>
<div class="line"><a id="l00445" name="l00445"></a><span class="lineno">  445</span><span class="comment"></span> </div>
<div class="line"><a id="l00446" name="l00446"></a><span class="lineno">  446</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00447" name="l00447"></a><span class="lineno">  447</span><span class="comment">   * Main ctor, creating a new functioning builder according to the knobs in `Config config` arg.</span></div>
<div class="line"><a id="l00448" name="l00448"></a><span class="lineno">  448</span><span class="comment">   *</span></div>
<div class="line"><a id="l00449" name="l00449"></a><span class="lineno">  449</span><span class="comment">   * @param config</span></div>
<div class="line"><a id="l00450" name="l00450"></a><span class="lineno">  450</span><span class="comment">   *        Struct_reader::Config storing the knobs controlling how `*this` will work.</span></div>
<div class="line"><a id="l00451" name="l00451"></a><span class="lineno">  451</span><span class="comment">   */</span></div>
<div class="line"><a id="l00452" name="l00452"></a><span class="lineno"><a class="line" href="classipc_1_1transport_1_1struc_1_1Struct__reader.html#a8395ee937193713e413c36c144ea9a30">  452</a></span>  <span class="keyword">explicit</span> <a class="code hl_function" href="classipc_1_1transport_1_1struc_1_1Struct__reader.html#a8395ee937193713e413c36c144ea9a30">Struct_reader</a>(<span class="keyword">const</span> <a class="code hl_struct" href="structipc_1_1transport_1_1struc_1_1Struct__reader_1_1Config.html">Config</a>&amp; config)</div>
<div class="line"><a id="l00453" name="l00453"></a><span class="lineno">  453</span> </div>
<div class="line"><a id="l00454" name="l00454"></a><span class="lineno">  454</span>  <span class="comment">/// Disallow copy construction.</span></div>
<div class="line"><a id="l00455" name="l00455"></a><span class="lineno">  455</span>  <a class="code hl_function" href="classipc_1_1transport_1_1struc_1_1Struct__reader.html#a4dc980273439330d6d2359e764c7680a">Struct_reader</a>(<span class="keyword">const</span> <a class="code hl_class" href="classipc_1_1transport_1_1struc_1_1Struct__reader.html">Struct_reader</a>&amp;) = <span class="keyword">delete</span>;</div>
<div class="line"><a id="l00456" name="l00456"></a><span class="lineno">  456</span><span class="comment"></span> </div>
<div class="line"><a id="l00457" name="l00457"></a><span class="lineno">  457</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00458" name="l00458"></a><span class="lineno">  458</span><span class="comment">   * Move-constructs `*this` to be equal to `src`, while `src` becomes as-if defaulted-cted.</span></div>
<div class="line"><a id="l00459" name="l00459"></a><span class="lineno">  459</span><span class="comment">   *</span></div>
<div class="line"><a id="l00460" name="l00460"></a><span class="lineno">  460</span><span class="comment">   * @param src</span></div>
<div class="line"><a id="l00461" name="l00461"></a><span class="lineno">  461</span><span class="comment">   *        Moved-from object that becomes as-if default-cted.</span></div>
<div class="line"><a id="l00462" name="l00462"></a><span class="lineno">  462</span><span class="comment">   */</span></div>
<div class="line"><a id="l00463" name="l00463"></a><span class="lineno"><a class="line" href="classipc_1_1transport_1_1struc_1_1Struct__reader.html#a6056a8c7cc94fd4ebe6f55054518cd4d">  463</a></span>  <a class="code hl_function" href="classipc_1_1transport_1_1struc_1_1Struct__reader.html#a6056a8c7cc94fd4ebe6f55054518cd4d">Struct_reader</a>(<a class="code hl_class" href="classipc_1_1transport_1_1struc_1_1Struct__reader.html">Struct_reader</a>&amp;&amp; src);</div>
<div class="line"><a id="l00464" name="l00464"></a><span class="lineno">  464</span><span class="comment"></span> </div>
<div class="line"><a id="l00465" name="l00465"></a><span class="lineno">  465</span><span class="comment">  /// Destructor.  Do not use the `Reader` `deserialization()` or any copies thereof past this.</span></div>
<div class="line"><a id="l00466" name="l00466"></a><span class="lineno"><a class="line" href="classipc_1_1transport_1_1struc_1_1Struct__reader.html#a66ccf2eda9b6302a98b0f326292332d2">  466</a></span><span class="comment"></span>  <a class="code hl_function" href="classipc_1_1transport_1_1struc_1_1Struct__reader.html#a66ccf2eda9b6302a98b0f326292332d2">~Struct_reader</a>();</div>
<div class="line"><a id="l00467" name="l00467"></a><span class="lineno">  467</span> </div>
<div class="line"><a id="l00468" name="l00468"></a><span class="lineno">  468</span>  <span class="comment">// Methods.</span></div>
<div class="line"><a id="l00469" name="l00469"></a><span class="lineno">  469</span><span class="comment"></span> </div>
<div class="line"><a id="l00470" name="l00470"></a><span class="lineno">  470</span><span class="comment">  /// Disallow copy assignment.</span></div>
<div class="line"><a id="l00471" name="l00471"></a><span class="lineno"><a class="line" href="classipc_1_1transport_1_1struc_1_1Struct__reader.html#ad82bfcf62d6e0e2c11266876dcc5714c">  471</a></span><span class="comment"></span>  <a class="code hl_class" href="classipc_1_1transport_1_1struc_1_1Struct__reader.html">Struct_reader</a>&amp; <a class="code hl_function" href="classipc_1_1transport_1_1struc_1_1Struct__reader.html#ad82bfcf62d6e0e2c11266876dcc5714c">operator=</a>(<span class="keyword">const</span> <a class="code hl_class" href="classipc_1_1transport_1_1struc_1_1Struct__reader.html">Struct_reader</a>&amp;) = <span class="keyword">delete</span>;</div>
<div class="line"><a id="l00472" name="l00472"></a><span class="lineno">  472</span><span class="comment"></span> </div>
<div class="line"><a id="l00473" name="l00473"></a><span class="lineno">  473</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00474" name="l00474"></a><span class="lineno">  474</span><span class="comment">   * Move-assigns `*this` to be equal to `src`, while `src` becomes as-if defaulted-cted; or no-op</span></div>
<div class="line"><a id="l00475" name="l00475"></a><span class="lineno">  475</span><span class="comment">   * if `&amp;src == this`.</span></div>
<div class="line"><a id="l00476" name="l00476"></a><span class="lineno">  476</span><span class="comment">   *</span></div>
<div class="line"><a id="l00477" name="l00477"></a><span class="lineno">  477</span><span class="comment">   * @param src</span></div>
<div class="line"><a id="l00478" name="l00478"></a><span class="lineno">  478</span><span class="comment">   *        Moved-from object that becomes as-if default-cted, unless it is `*this`.</span></div>
<div class="line"><a id="l00479" name="l00479"></a><span class="lineno">  479</span><span class="comment">   * @return `*this`.</span></div>
<div class="line"><a id="l00480" name="l00480"></a><span class="lineno">  480</span><span class="comment">   */</span></div>
<div class="line"><a id="l00481" name="l00481"></a><span class="lineno"><a class="line" href="classipc_1_1transport_1_1struc_1_1Struct__reader.html#a89a0f2dd586d9c74c532a644b568d871">  481</a></span>  <a class="code hl_class" href="classipc_1_1transport_1_1struc_1_1Struct__reader.html">Struct_reader</a>&amp; <a class="code hl_function" href="classipc_1_1transport_1_1struc_1_1Struct__reader.html#a89a0f2dd586d9c74c532a644b568d871">operator=</a>(<a class="code hl_class" href="classipc_1_1transport_1_1struc_1_1Struct__reader.html">Struct_reader</a>&amp;&amp; src);</div>
<div class="line"><a id="l00482" name="l00482"></a><span class="lineno">  482</span> </div>
<div class="line"><a id="l00483" name="l00483"></a><span class="lineno">  483</span>  <span class="comment">// Methods.</span></div>
<div class="line"><a id="l00484" name="l00484"></a><span class="lineno">  484</span><span class="comment"></span> </div>
<div class="line"><a id="l00485" name="l00485"></a><span class="lineno">  485</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00486" name="l00486"></a><span class="lineno">  486</span><span class="comment">   * Prior to deserialization() obtains a memory area `max_sz` bytes long into which the user may write-to</span></div>
<div class="line"><a id="l00487" name="l00487"></a><span class="lineno">  487</span><span class="comment">   * until the next add_serialization_segment(), deserialization(), or dtor call (whichever happens first);</span></div>
<div class="line"><a id="l00488" name="l00488"></a><span class="lineno">  488</span><span class="comment">   * returns a pointer to that area as described by the pointed-to `Blob`&#39;s [`begin()`, `end()`) range.</span></div>
<div class="line"><a id="l00489" name="l00489"></a><span class="lineno">  489</span><span class="comment">   * If the concept impl decides `max_sz` bytes are not available, returns null.  `*this` shall not be used</span></div>
<div class="line"><a id="l00490" name="l00490"></a><span class="lineno">  490</span><span class="comment">   * subsequent to such an eventuality.</span></div>
<div class="line"><a id="l00491" name="l00491"></a><span class="lineno">  491</span><span class="comment">   *</span></div>
<div class="line"><a id="l00492" name="l00492"></a><span class="lineno">  492</span><span class="comment">   * To use deserialization() subsequently, you must:</span></div>
<div class="line"><a id="l00493" name="l00493"></a><span class="lineno">  493</span><span class="comment">   *   - call this at least once (successfully);</span></div>
<div class="line"><a id="l00494" name="l00494"></a><span class="lineno">  494</span><span class="comment">   *   - call this (N - 1) more times (successfully), where N is the number of segments produced by the counterpart</span></div>
<div class="line"><a id="l00495" name="l00495"></a><span class="lineno">  495</span><span class="comment">   *     Struct_builder.</span></div>
<div class="line"><a id="l00496" name="l00496"></a><span class="lineno">  496</span><span class="comment">   *     - So N &gt;= 1 by definition.</span></div>
<div class="line"><a id="l00497" name="l00497"></a><span class="lineno">  497</span><span class="comment">   *</span></div>
<div class="line"><a id="l00498" name="l00498"></a><span class="lineno">  498</span><span class="comment">   * The required sequence for each in-segment is:</span></div>
<div class="line"><a id="l00499" name="l00499"></a><span class="lineno">  499</span><span class="comment">   *   - Call add_serialization_segment(), which yields pointer to a `Blob`.</span></div>
<div class="line"><a id="l00500" name="l00500"></a><span class="lineno">  500</span><span class="comment">   *   - Write segment serialization into (some subrange of) that `Blob`&#39;s [`begin()`, `end()`) range</span></div>
<div class="line"><a id="l00501" name="l00501"></a><span class="lineno">  501</span><span class="comment">   *     (presumably directly out of the transport).</span></div>
<div class="line"><a id="l00502" name="l00502"></a><span class="lineno">  502</span><span class="comment">   *   - Adjust said `Blob`&#39;s [`begin()`, `end()`) range to contain exactly the serialization segment.</span></div>
<div class="line"><a id="l00503" name="l00503"></a><span class="lineno">  503</span><span class="comment">   *     - You may use `.resize()` or its convenience wrappers `.start_past_prefix()` and `.start_past_prefix_inc()`.</span></div>
<div class="line"><a id="l00504" name="l00504"></a><span class="lineno">  504</span><span class="comment">   *       Use these to (1) mark the actual segment&#39;s size (which may well be &lt; `max_sz`) and (2)</span></div>
<div class="line"><a id="l00505" name="l00505"></a><span class="lineno">  505</span><span class="comment">   *       discard any framing data that came in together with the segment serialization.</span></div>
<div class="line"><a id="l00506" name="l00506"></a><span class="lineno">  506</span><span class="comment">   *     - You may not `.make_zero()` (or behavior is undefined).</span></div>
<div class="line"><a id="l00507" name="l00507"></a><span class="lineno">  507</span><span class="comment">   *     - You may not use `.resize()` and friends to cause `begin()` to go left or `end()` to go right.</span></div>
<div class="line"><a id="l00508" name="l00508"></a><span class="lineno">  508</span><span class="comment">   *       They can only remain unchanged or travel right and left respectively (the range&#39;s edges cannot &quot;extend&quot;</span></div>
<div class="line"><a id="l00509" name="l00509"></a><span class="lineno">  509</span><span class="comment">   *       past the original range provided).</span></div>
<div class="line"><a id="l00510" name="l00510"></a><span class="lineno">  510</span><span class="comment">   *</span></div>
<div class="line"><a id="l00511" name="l00511"></a><span class="lineno">  511</span><span class="comment">   * After these steps, either add_serialization_segment() again (if more segments are forthcoming), or</span></div>
<div class="line"><a id="l00512" name="l00512"></a><span class="lineno">  512</span><span class="comment">   * call deserialization() (to use the structured data), or invoke dtor (if `*this` is no longer of interest).</span></div>
<div class="line"><a id="l00513" name="l00513"></a><span class="lineno">  513</span><span class="comment">   *</span></div>
<div class="line"><a id="l00514" name="l00514"></a><span class="lineno">  514</span><span class="comment">   * ### Alignment ###</span></div>
<div class="line"><a id="l00515" name="l00515"></a><span class="lineno">  515</span><span class="comment">   * The returned `Blob`&#39;s begin-to-end range shall be word-aligned, meaning `.const_data()` shall be on a word</span></div>
<div class="line"><a id="l00516" name="l00516"></a><span class="lineno">  516</span><span class="comment">   * boundary, meaning the numeric value thereof shall be a multiple of `sizeof(void*)`.  This is the guarantee</span></div>
<div class="line"><a id="l00517" name="l00517"></a><span class="lineno">  517</span><span class="comment">   * of add_serialization_segment().</span></div>
<div class="line"><a id="l00518" name="l00518"></a><span class="lineno">  518</span><span class="comment">   *</span></div>
<div class="line"><a id="l00519" name="l00519"></a><span class="lineno">  519</span><span class="comment">   * Accordingly, any `.resize()` (etc.) done on the returned `Blob` by the user *must* result in a</span></div>
<div class="line"><a id="l00520" name="l00520"></a><span class="lineno">  520</span><span class="comment">   * `.const_data()` (a/k/a `.begin()`) that is *still* word-aligned by the same definition.  Informally there</span></div>
<div class="line"><a id="l00521" name="l00521"></a><span class="lineno">  521</span><span class="comment">   * are ~2 ways to guarantee this on the user&#39;s part:</span></div>
<div class="line"><a id="l00522" name="l00522"></a><span class="lineno">  522</span><span class="comment">   *   - Just don&#39;t change `begin()` (do not use prefix frame data; you may use postfix frame data instead).  Or:</span></div>
<div class="line"><a id="l00523" name="l00523"></a><span class="lineno">  523</span><span class="comment">   *   - If you require frame data to live in front of the segment, in your protocol ensure that</span></div>
<div class="line"><a id="l00524" name="l00524"></a><span class="lineno">  524</span><span class="comment">   *     the size of such frame data is a multiple of `sizeof(void*)`.</span></div>
<div class="line"><a id="l00525" name="l00525"></a><span class="lineno">  525</span><span class="comment">   *</span></div>
<div class="line"><a id="l00526" name="l00526"></a><span class="lineno">  526</span><span class="comment">   * @param max_sz</span></div>
<div class="line"><a id="l00527" name="l00527"></a><span class="lineno">  527</span><span class="comment">   *        `Blob` to which the returned pointer points shall have `.size() == max_sz`.</span></div>
<div class="line"><a id="l00528" name="l00528"></a><span class="lineno">  528</span><span class="comment">   *        (It may have equal or larger `.capacity()`.)  See above.</span></div>
<div class="line"><a id="l00529" name="l00529"></a><span class="lineno">  529</span><span class="comment">   * @return Pointer to the `Blob` inside which to place, subsequently, the next segment&#39;s contents.  See above.</span></div>
<div class="line"><a id="l00530" name="l00530"></a><span class="lineno">  530</span><span class="comment">   */</span></div>
<div class="line"><a id="l00531" name="l00531"></a><span class="lineno"><a class="line" href="classipc_1_1transport_1_1struc_1_1Struct__reader.html#ae450aff09cc9d71b75b382d59a9cfc23">  531</a></span>  flow::util::Blob* <a class="code hl_function" href="classipc_1_1transport_1_1struc_1_1Struct__reader.html#ae450aff09cc9d71b75b382d59a9cfc23">add_serialization_segment</a>(<span class="keywordtype">size_t</span> max_sz);</div>
<div class="line"><a id="l00532" name="l00532"></a><span class="lineno">  532</span><span class="comment"></span> </div>
<div class="line"><a id="l00533" name="l00533"></a><span class="lineno">  533</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00534" name="l00534"></a><span class="lineno">  534</span><span class="comment">   * After all serialization segments have been acquired in RAM via add_serialization_segment() and finalized</span></div>
<div class="line"><a id="l00535" name="l00535"></a><span class="lineno">  535</span><span class="comment">   * via begin-end-range adjustment, this returns a reference to the reader object whose capnp-generated</span></div>
<div class="line"><a id="l00536" name="l00536"></a><span class="lineno">  536</span><span class="comment">   * accessors can read the structured contents of `*this`.  Behavior is undefined if this is called before all</span></div>
<div class="line"><a id="l00537" name="l00537"></a><span class="lineno">  537</span><span class="comment">   * add_serialization_segment() calls have been made (and they must have been successful).  Behavior is undefined</span></div>
<div class="line"><a id="l00538" name="l00538"></a><span class="lineno">  538</span><span class="comment">   * if add_serialization_segment() is called after this is called.</span></div>
<div class="line"><a id="l00539" name="l00539"></a><span class="lineno">  539</span><span class="comment">   *</span></div>
<div class="line"><a id="l00540" name="l00540"></a><span class="lineno">  540</span><span class="comment">   * deserialization() shall be called no more than once.</span></div>
<div class="line"><a id="l00541" name="l00541"></a><span class="lineno">  541</span><span class="comment">   *</span></div>
<div class="line"><a id="l00542" name="l00542"></a><span class="lineno">  542</span><span class="comment">   * The returned `Reader` shall remain valid until `*this` is destroyed.  (Therefore any copies thereof</span></div>
<div class="line"><a id="l00543" name="l00543"></a><span class="lineno">  543</span><span class="comment">   * shall also be valid in the same time frame.  However there is no perf benefit to making such copies, and</span></div>
<div class="line"><a id="l00544" name="l00544"></a><span class="lineno">  544</span><span class="comment">   * there is likely a small penalty to doing so.)</span></div>
<div class="line"><a id="l00545" name="l00545"></a><span class="lineno">  545</span><span class="comment">   *</span></div>
<div class="line"><a id="l00546" name="l00546"></a><span class="lineno">  546</span><span class="comment">   * @tparam Struct</span></div>
<div class="line"><a id="l00547" name="l00547"></a><span class="lineno">  547</span><span class="comment">   *         Same meaning as in the vanilla capnp use of `MessageReader::getRoot&lt;Struct&gt;()`.</span></div>
<div class="line"><a id="l00548" name="l00548"></a><span class="lineno">  548</span><span class="comment">   * @param err_code</span></div>
<div class="line"><a id="l00549" name="l00549"></a><span class="lineno">  549</span><span class="comment">   *        See `flow::Error_code` docs for error reporting semantics.  #Error_code generated:</span></div>
<div class="line"><a id="l00550" name="l00550"></a><span class="lineno">  550</span><span class="comment">   *        error::Code::S_DESERIALIZE_FAILED_INSUFFICIENT_SEGMENTS (add_serialization_segment() was called</span></div>
<div class="line"><a id="l00551" name="l00551"></a><span class="lineno">  551</span><span class="comment">   *        an insufficient number of times; in particular 0 times always triggers this);</span></div>
<div class="line"><a id="l00552" name="l00552"></a><span class="lineno">  552</span><span class="comment">   *        error::Code::S_DESERIALIZE_FAILED_SEGMENT_MISALIGNED (add_serialization_segment() was called with</span></div>
<div class="line"><a id="l00553" name="l00553"></a><span class="lineno">  553</span><span class="comment">   *        a segment that starts at a misaligned address);</span></div>
<div class="line"><a id="l00554" name="l00554"></a><span class="lineno">  554</span><span class="comment">   *        implementation may also emit other errors.</span></div>
<div class="line"><a id="l00555" name="l00555"></a><span class="lineno">  555</span><span class="comment">   * @return See above.  If and only if `err_code` is non-null, and truthy `*err_code` is emitted, a useless</span></div>
<div class="line"><a id="l00556" name="l00556"></a><span class="lineno">  556</span><span class="comment">   *         (default-cted) `Reader` is returned.</span></div>
<div class="line"><a id="l00557" name="l00557"></a><span class="lineno">  557</span><span class="comment">   */</span></div>
<div class="line"><a id="l00558" name="l00558"></a><span class="lineno">  558</span>  <span class="keyword">template</span>&lt;<span class="keyword">typename</span> Struct&gt;</div>
<div class="line"><a id="l00559" name="l00559"></a><span class="lineno"><a class="line" href="classipc_1_1transport_1_1struc_1_1Struct__reader.html#a95576f8cd8ad45a720276bd074cea4f2">  559</a></span>  <span class="keyword">typename</span> <a class="code hl_typedef" href="namespaceipc_1_1transport_1_1struc_1_1shm_1_1classic.html#af94f8698ca62a84d6366aaa931375d41">Struct::Reader</a> <a class="code hl_function" href="classipc_1_1transport_1_1struc_1_1Struct__reader.html#a95576f8cd8ad45a720276bd074cea4f2">deserialization</a>(<a class="code hl_typedef" href="namespaceipc.html#aa3192e586cc45d3e7c22463bf2760f89">Error_code</a>* err_code = 0);</div>
<div class="line"><a id="l00560" name="l00560"></a><span class="lineno">  560</span>}; <span class="comment">// class Struct_reader</span></div>
<div class="line"><a id="l00561" name="l00561"></a><span class="lineno">  561</span> </div>
<div class="line"><a id="l00562" name="l00562"></a><span class="lineno">  562</span>} <span class="comment">// namespace ipc::transport::struc</span></div>
<div class="line"><a id="l00563" name="l00563"></a><span class="lineno">  563</span> </div>
<div class="line"><a id="l00564" name="l00564"></a><span class="lineno">  564</span><span class="preprocessor">#endif </span><span class="comment">// IPC_DOXYGEN_ONLY</span></div>
<div class="ttc" id="aclassCapnp__msg__builder__interface_html"><div class="ttname"><a href="classCapnp__msg__builder__interface.html">Capnp_msg_builder_interface</a></div></div>
<div class="ttc" id="aclassipc_1_1transport_1_1struc_1_1Struct__builder_html"><div class="ttname"><a href="classipc_1_1transport_1_1struc_1_1Struct__builder.html">ipc::transport::struc::Struct_builder</a></div><div class="ttdoc">A documentation-only concept defining the behavior of an object capable of zero-copy-serializing,...</div><div class="ttdef"><b>Definition:</b> <a href="ipc__transport__structured_2src_2ipc_2transport_2struc_2serializer_8hpp_source.html#l00197">serializer.hpp:198</a></div></div>
<div class="ttc" id="aclassipc_1_1transport_1_1struc_1_1Struct__builder_html_a008f6b6456a4b2dab63cdda5f9e4cfe5"><div class="ttname"><a href="classipc_1_1transport_1_1struc_1_1Struct__builder.html#a008f6b6456a4b2dab63cdda5f9e4cfe5">ipc::transport::struc::Struct_builder::~Struct_builder</a></div><div class="ttdeci">~Struct_builder()</div><div class="ttdoc">Destructor. Do not use *payload_msg_builder() or any copies thereof past this.</div></div>
<div class="ttc" id="aclassipc_1_1transport_1_1struc_1_1Struct__builder_html_a1899e36ae85a208f3208adfaeb5f0000"><div class="ttname"><a href="classipc_1_1transport_1_1struc_1_1Struct__builder.html#a1899e36ae85a208f3208adfaeb5f0000">ipc::transport::struc::Struct_builder::operator=</a></div><div class="ttdeci">Struct_builder &amp; operator=(const Struct_builder &amp;)=delete</div><div class="ttdoc">Disallow copy assignment.</div></div>
<div class="ttc" id="aclassipc_1_1transport_1_1struc_1_1Struct__builder_html_a2c413c604b1d6abf63ce1589367dd772"><div class="ttname"><a href="classipc_1_1transport_1_1struc_1_1Struct__builder.html#a2c413c604b1d6abf63ce1589367dd772">ipc::transport::struc::Struct_builder::Struct_builder</a></div><div class="ttdeci">Struct_builder(Struct_builder &amp;&amp;src)</div><div class="ttdoc">Move-constructs *this to be equal to src, while src becomes as-if defaulted-cted.</div></div>
<div class="ttc" id="aclassipc_1_1transport_1_1struc_1_1Struct__builder_html_a460aa187c0aaa5adfb81ecc902c7eca9"><div class="ttname"><a href="classipc_1_1transport_1_1struc_1_1Struct__builder.html#a460aa187c0aaa5adfb81ecc902c7eca9">ipc::transport::struc::Struct_builder::Struct_builder</a></div><div class="ttdeci">Struct_builder()</div><div class="ttdoc">Default ctor, leaving *this in a state only suitable for destruction or being moved-to.</div></div>
<div class="ttc" id="aclassipc_1_1transport_1_1struc_1_1Struct__builder_html_a708a66e9598c75a1f54828a4805da4f0"><div class="ttname"><a href="classipc_1_1transport_1_1struc_1_1Struct__builder.html#a708a66e9598c75a1f54828a4805da4f0">ipc::transport::struc::Struct_builder::operator=</a></div><div class="ttdeci">Struct_builder &amp; operator=(Struct_builder &amp;&amp;src)</div><div class="ttdoc">Move-assigns *this to be equal to src, while src becomes as-if defaulted-cted; or no-op if &amp;src == th...</div></div>
<div class="ttc" id="aclassipc_1_1transport_1_1struc_1_1Struct__builder_html_a9a4b9587c162f85ad4d3e0a5fad8dffb"><div class="ttname"><a href="classipc_1_1transport_1_1struc_1_1Struct__builder.html#a9a4b9587c162f85ad4d3e0a5fad8dffb">ipc::transport::struc::Struct_builder::payload_msg_builder</a></div><div class="ttdeci">Capnp_msg_builder_interface * payload_msg_builder()</div><div class="ttdoc">Pointer to the payload Capnp_msg_builder_interface, suitable for mutation by the user.</div></div>
<div class="ttc" id="aclassipc_1_1transport_1_1struc_1_1Struct__builder_html_ab90424897efed06ffc6b0884761fb31f"><div class="ttname"><a href="classipc_1_1transport_1_1struc_1_1Struct__builder.html#ab90424897efed06ffc6b0884761fb31f">ipc::transport::struc::Struct_builder::Session</a></div><div class="ttdeci">unspecified Session</div><div class="ttdoc">Type objects of which specify to emit_serialization() the opposing recipient for which the serializat...</div><div class="ttdef"><b>Definition:</b> <a href="ipc__transport__structured_2src_2ipc_2transport_2struc_2serializer_8hpp_source.html#l00248">serializer.hpp:248</a></div></div>
<div class="ttc" id="aclassipc_1_1transport_1_1struc_1_1Struct__builder_html_ad98eba0fc5a8b377253eac797a9a117e"><div class="ttname"><a href="classipc_1_1transport_1_1struc_1_1Struct__builder.html#ad98eba0fc5a8b377253eac797a9a117e">ipc::transport::struc::Struct_builder::Struct_builder</a></div><div class="ttdeci">Struct_builder(const Config &amp;config) Struct_builder(const Struct_builder &amp;)=delete</div><div class="ttdoc">Main ctor, creating a new builder according to the knobs in Config config arg.</div></div>
<div class="ttc" id="aclassipc_1_1transport_1_1struc_1_1Struct__builder_html_ae1516b0d68c48f2e13baf6aca366ac6c"><div class="ttname"><a href="classipc_1_1transport_1_1struc_1_1Struct__builder.html#ae1516b0d68c48f2e13baf6aca366ac6c">ipc::transport::struc::Struct_builder::n_serialization_segments</a></div><div class="ttdeci">size_t n_serialization_segments() const</div><div class="ttdoc">Returns what target_blobs.size() would return after calling emit_serialization(&amp;target_blobs) (with a...</div></div>
<div class="ttc" id="aclassipc_1_1transport_1_1struc_1_1Struct__builder_html_af5085934123f075c6d0701e9e45e4bcc"><div class="ttname"><a href="classipc_1_1transport_1_1struc_1_1Struct__builder.html#af5085934123f075c6d0701e9e45e4bcc">ipc::transport::struc::Struct_builder::emit_serialization</a></div><div class="ttdeci">void emit_serialization(Segment_ptrs *target_blobs, const Session &amp;session, Error_code *err_code=0) const</div><div class="ttdoc">Returns the serialization in the form of a sequence of 1+ pointers to Blobs which are guaranteed to r...</div></div>
<div class="ttc" id="aclassipc_1_1transport_1_1struc_1_1Struct__reader_html"><div class="ttname"><a href="classipc_1_1transport_1_1struc_1_1Struct__reader.html">ipc::transport::struc::Struct_reader</a></div><div class="ttdoc">A documentation-only concept that is, conceptually, roughly what capnp::MessageReader is to capnp::Me...</div><div class="ttdef"><b>Definition:</b> <a href="ipc__transport__structured_2src_2ipc_2transport_2struc_2serializer_8hpp_source.html#l00412">serializer.hpp:413</a></div></div>
<div class="ttc" id="aclassipc_1_1transport_1_1struc_1_1Struct__reader_html_a4dc980273439330d6d2359e764c7680a"><div class="ttname"><a href="classipc_1_1transport_1_1struc_1_1Struct__reader.html#a4dc980273439330d6d2359e764c7680a">ipc::transport::struc::Struct_reader::Struct_reader</a></div><div class="ttdeci">Struct_reader()</div><div class="ttdoc">Default ctor, leaving *this in a state only suitable for destruction or being moved-to.</div></div>
<div class="ttc" id="aclassipc_1_1transport_1_1struc_1_1Struct__reader_html_a6056a8c7cc94fd4ebe6f55054518cd4d"><div class="ttname"><a href="classipc_1_1transport_1_1struc_1_1Struct__reader.html#a6056a8c7cc94fd4ebe6f55054518cd4d">ipc::transport::struc::Struct_reader::Struct_reader</a></div><div class="ttdeci">Struct_reader(Struct_reader &amp;&amp;src)</div><div class="ttdoc">Move-constructs *this to be equal to src, while src becomes as-if defaulted-cted.</div></div>
<div class="ttc" id="aclassipc_1_1transport_1_1struc_1_1Struct__reader_html_a66ccf2eda9b6302a98b0f326292332d2"><div class="ttname"><a href="classipc_1_1transport_1_1struc_1_1Struct__reader.html#a66ccf2eda9b6302a98b0f326292332d2">ipc::transport::struc::Struct_reader::~Struct_reader</a></div><div class="ttdeci">~Struct_reader()</div><div class="ttdoc">Destructor. Do not use the Reader deserialization() or any copies thereof past this.</div></div>
<div class="ttc" id="aclassipc_1_1transport_1_1struc_1_1Struct__reader_html_a8395ee937193713e413c36c144ea9a30"><div class="ttname"><a href="classipc_1_1transport_1_1struc_1_1Struct__reader.html#a8395ee937193713e413c36c144ea9a30">ipc::transport::struc::Struct_reader::Struct_reader</a></div><div class="ttdeci">Struct_reader(const Config &amp;config) Struct_reader(const Struct_reader &amp;)=delete</div><div class="ttdoc">Main ctor, creating a new functioning builder according to the knobs in Config config arg.</div></div>
<div class="ttc" id="aclassipc_1_1transport_1_1struc_1_1Struct__reader_html_a89a0f2dd586d9c74c532a644b568d871"><div class="ttname"><a href="classipc_1_1transport_1_1struc_1_1Struct__reader.html#a89a0f2dd586d9c74c532a644b568d871">ipc::transport::struc::Struct_reader::operator=</a></div><div class="ttdeci">Struct_reader &amp; operator=(Struct_reader &amp;&amp;src)</div><div class="ttdoc">Move-assigns *this to be equal to src, while src becomes as-if defaulted-cted; or no-op if &amp;src == th...</div></div>
<div class="ttc" id="aclassipc_1_1transport_1_1struc_1_1Struct__reader_html_a95576f8cd8ad45a720276bd074cea4f2"><div class="ttname"><a href="classipc_1_1transport_1_1struc_1_1Struct__reader.html#a95576f8cd8ad45a720276bd074cea4f2">ipc::transport::struc::Struct_reader::deserialization</a></div><div class="ttdeci">Struct::Reader deserialization(Error_code *err_code=0)</div><div class="ttdoc">After all serialization segments have been acquired in RAM via add_serialization_segment() and finali...</div></div>
<div class="ttc" id="aclassipc_1_1transport_1_1struc_1_1Struct__reader_html_ad82bfcf62d6e0e2c11266876dcc5714c"><div class="ttname"><a href="classipc_1_1transport_1_1struc_1_1Struct__reader.html#ad82bfcf62d6e0e2c11266876dcc5714c">ipc::transport::struc::Struct_reader::operator=</a></div><div class="ttdeci">Struct_reader &amp; operator=(const Struct_reader &amp;)=delete</div><div class="ttdoc">Disallow copy assignment.</div></div>
<div class="ttc" id="aclassipc_1_1transport_1_1struc_1_1Struct__reader_html_ae450aff09cc9d71b75b382d59a9cfc23"><div class="ttname"><a href="classipc_1_1transport_1_1struc_1_1Struct__reader.html#ae450aff09cc9d71b75b382d59a9cfc23">ipc::transport::struc::Struct_reader::add_serialization_segment</a></div><div class="ttdeci">flow::util::Blob * add_serialization_segment(size_t max_sz)</div><div class="ttdoc">Prior to deserialization() obtains a memory area max_sz bytes long into which the user may write-to u...</div></div>
<div class="ttc" id="anamespaceipc_1_1transport_1_1struc_1_1shm_1_1classic_html_af94f8698ca62a84d6366aaa931375d41"><div class="ttname"><a href="namespaceipc_1_1transport_1_1struc_1_1shm_1_1classic.html#af94f8698ca62a84d6366aaa931375d41">ipc::transport::struc::shm::classic::Reader</a></div><div class="ttdeci">Reader&lt; ipc::shm::classic::Pool_arena &gt; Reader</div><div class="ttdoc">Convenience alias: transport::struc::shm::Reader that works with boost.ipc.shm pools from ipc::shm::c...</div><div class="ttdef"><b>Definition:</b> <a href="transport_2struc_2shm_2classic_2classic__fwd_8hpp_source.html#l00039">classic_fwd.hpp:39</a></div></div>
<div class="ttc" id="anamespaceipc_1_1transport_1_1struc_html"><div class="ttname"><a href="namespaceipc_1_1transport_1_1struc.html">ipc::transport::struc</a></div><div class="ttdoc">Sub-module of Flow-IPC module ipc::transport providing transmission of structured messages specifical...</div><div class="ttdef"><b>Definition:</b> <a href="ipc__transport__structured_2src_2ipc_2transport_2struc_2channel_8cpp_source.html#l00030">channel.cpp:31</a></div></div>
<div class="ttc" id="anamespaceipc_1_1transport_1_1struc_html_a82a69eaa39cbe8a002de1266f1cbb5cb"><div class="ttname"><a href="namespaceipc_1_1transport_1_1struc.html#a82a69eaa39cbe8a002de1266f1cbb5cb">ipc::transport::struc::Segment_ptrs</a></div><div class="ttdeci">std::vector&lt; flow::util::Blob * &gt; Segment_ptrs</div><div class="ttdoc">Sequence of 1+ Blob pointers to blobs which must stay alive while these pointers may be dereferenced,...</div><div class="ttdef"><b>Definition:</b> <a href="struc__fwd_8hpp_source.html#l00122">struc_fwd.hpp:122</a></div></div>
<div class="ttc" id="anamespaceipc_html_aa3192e586cc45d3e7c22463bf2760f89"><div class="ttname"><a href="namespaceipc.html#aa3192e586cc45d3e7c22463bf2760f89">ipc::Error_code</a></div><div class="ttdeci">flow::Error_code Error_code</div><div class="ttdoc">Short-hand for flow::Error_code which is very common.</div><div class="ttdef"><b>Definition:</b> <a href="common_8hpp_source.html#l00298">common.hpp:298</a></div></div>
<div class="ttc" id="astructipc_1_1transport_1_1struc_1_1Struct__builder_1_1Config_html"><div class="ttname"><a href="structipc_1_1transport_1_1struc_1_1Struct__builder_1_1Config.html">ipc::transport::struc::Struct_builder::Config</a></div><div class="ttdoc">Copy-ctible, copy-assignable, default-ctible type – informally, cheaply copyable and likely an aggreg...</div><div class="ttdef"><b>Definition:</b> <a href="ipc__transport__structured_2src_2ipc_2transport_2struc_2serializer_8hpp_source.html#l00222">serializer.hpp:223</a></div></div>
<div class="ttc" id="astructipc_1_1transport_1_1struc_1_1Struct__builder_1_1Config_html_a267bcfe82c950040af5089543227a57e"><div class="ttname"><a href="structipc_1_1transport_1_1struc_1_1Struct__builder_1_1Config.html#a267bcfe82c950040af5089543227a57e">ipc::transport::struc::Struct_builder::Config::m_example_val</a></div><div class="ttdeci">example_t m_example_val</div><div class="ttdoc">Or like this one.</div><div class="ttdef"><b>Definition:</b> <a href="ipc__transport__structured_2src_2ipc_2transport_2struc_2serializer_8hpp_source.html#l00239">serializer.hpp:239</a></div></div>
<div class="ttc" id="astructipc_1_1transport_1_1struc_1_1Struct__builder_1_1Config_html_a855ec0521ca4f2a2a841d2a25ee6f12a"><div class="ttname"><a href="structipc_1_1transport_1_1struc_1_1Struct__builder_1_1Config.html#a855ec0521ca4f2a2a841d2a25ee6f12a">ipc::transport::struc::Struct_builder::Config::m_example_struct</a></div><div class="ttdeci">Example_type m_example_struct</div><div class="ttdoc">An arbitrary, but cheaply-copyable in aggregate, set of knobs like (e.g.) this one follow.</div><div class="ttdef"><b>Definition:</b> <a href="ipc__transport__structured_2src_2ipc_2transport_2struc_2serializer_8hpp_source.html#l00236">serializer.hpp:236</a></div></div>
<div class="ttc" id="astructipc_1_1transport_1_1struc_1_1Struct__builder_1_1Config_html_ab818ec0d61c6c797f27222acc5fc0038"><div class="ttname"><a href="structipc_1_1transport_1_1struc_1_1Struct__builder_1_1Config.html#ab818ec0d61c6c797f27222acc5fc0038">ipc::transport::struc::Struct_builder::Config::m_logger_ptr</a></div><div class="ttdeci">flow::log::Logger m_logger_ptr</div><div class="ttdoc">First knob is typically the Logger* (null allowed) the Struct_builder will use.</div><div class="ttdef"><b>Definition:</b> <a href="ipc__transport__structured_2src_2ipc_2transport_2struc_2serializer_8hpp_source.html#l00233">serializer.hpp:233</a></div></div>
<div class="ttc" id="astructipc_1_1transport_1_1struc_1_1Struct__reader_1_1Config_html"><div class="ttname"><a href="structipc_1_1transport_1_1struc_1_1Struct__reader_1_1Config.html">ipc::transport::struc::Struct_reader::Config</a></div><div class="ttdoc">Analogous to Struct_builder::Config but for deserialization.</div><div class="ttdef"><b>Definition:</b> <a href="ipc__transport__structured_2src_2ipc_2transport_2struc_2serializer_8hpp_source.html#l00421">serializer.hpp:422</a></div></div>
<div class="ttc" id="astructipc_1_1transport_1_1struc_1_1Struct__reader_1_1Config_html_aab19f05acc30438dc887aaaa6ff8ae27"><div class="ttname"><a href="structipc_1_1transport_1_1struc_1_1Struct__reader_1_1Config.html#aab19f05acc30438dc887aaaa6ff8ae27">ipc::transport::struc::Struct_reader::Config::m_example_val</a></div><div class="ttdeci">example_t m_example_val</div><div class="ttdoc">Or yet another! Note in no way are these necessarily symmetric to Struct_builder::Config counterpart.</div><div class="ttdef"><b>Definition:</b> <a href="ipc__transport__structured_2src_2ipc_2transport_2struc_2serializer_8hpp_source.html#l00438">serializer.hpp:438</a></div></div>
<div class="ttc" id="astructipc_1_1transport_1_1struc_1_1Struct__reader_1_1Config_html_aee7630fa3413e39c1cec5f544ca0d8fe"><div class="ttname"><a href="structipc_1_1transport_1_1struc_1_1Struct__reader_1_1Config.html#aee7630fa3413e39c1cec5f544ca0d8fe">ipc::transport::struc::Struct_reader::Config::m_logger_ptr</a></div><div class="ttdeci">flow::log::Logger m_logger_ptr</div><div class="ttdoc">First knob is typically the Logger* (null allowed) the Struct_reader will use.</div><div class="ttdef"><b>Definition:</b> <a href="ipc__transport__structured_2src_2ipc_2transport_2struc_2serializer_8hpp_source.html#l00432">serializer.hpp:432</a></div></div>
<div class="ttc" id="astructipc_1_1transport_1_1struc_1_1Struct__reader_1_1Config_html_af3ab43e46bbae80b337a756e3e7083f1"><div class="ttname"><a href="structipc_1_1transport_1_1struc_1_1Struct__reader_1_1Config.html#af3ab43e46bbae80b337a756e3e7083f1">ipc::transport::struc::Struct_reader::Config::m_example_struct</a></div><div class="ttdeci">Example_type m_example_struct</div><div class="ttdoc">An arbitrary, but cheaply-copyable in aggregate, set of knobs like (e.g.) this one follow.</div><div class="ttdef"><b>Definition:</b> <a href="ipc__transport__structured_2src_2ipc_2transport_2struc_2serializer_8hpp_source.html#l00435">serializer.hpp:435</a></div></div>
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